DB2 Version 10.1 for Linux, UNIX, and Windows

Glossary

This glossary provides terms and definitions for DB2® for Linux, UNIX, and Windows software and other products.

The following cross-references are used in this glossary:

See refers you from a nonpreferred term to the preferred term or from an abbreviation to the spelled-out form.
See also refers you to a related or contrasting term.

For other terms and definitions, see the IBM Terminology website (opens in a new window).

Various definitions were reprinted with permission from the World Wide Web Consortium. For information about the Consortium, see the World Wide Web Consortium website (opens in a new window).

Special characters A B C D E F G H I J K L M N O P Q R S T U V W X Z

Special characters

.NET Framework: A Microsoft application development environment that consists of the common language runtime and .NET Framework class library that is designed to provide a consistent programming environment for developing and integrating code pieces. See also common language runtime.

A

abend

See abnormal end of task.

abend reason code

A 4-byte hexadecimal code that uniquely identifies a problem with a program that runs on the z/OS operating system.

abnormal end of task (abend)

The termination of a task, job, or subsystem because of an error condition that recovery facilities cannot resolve during execution.

abnormal termination

An exit that is not under program control, such as a trap or a segmentation violation.
A system failure or operator action that causes a job to end unsuccessfully.

absolute path

The full path name of an object. Absolute path names begin at the highest level, or root directory (which is identified by the forward slash (/) or backward slash (\) character). See also relative path.

access function

A user-provided function that converts the data type of text stored in a column to a type that can be processed by DB2 Net Search Extender and DB2 Text Search.

access path

The method that is selected by the database manager for retrieving data from a specific table. For example, an access path can involve the use of an index, a sequential scan, or a combination of the two.

access plan

The set of access paths that is selected by the query optimizer to evaluate a particular SQL or XQuery statement. The access plan specifies the order of operations to resolve the execution plan, the implementation methods (such as JOIN), and the access path for each table that is referenced in the statement.

access token

An object that contains security information for a process or thread, including the identity and privileges of the user account that is associated with the process or thread.

accounting string

User-defined accounting information that is sent to DRDA servers.

active agent

An agent that is processing a request for an application. See also idle agent.

active log

The primary and secondary log files that are currently needed for recovery and rollback. See also archive log.
A data set with a fixed size where recovery events are recorded as they occur. When the active log is full, the contents of the active log are copied to the archive log.

activity

A database entity that uses database resources during its lifetime, which can span one or more requests. A cursor and a procedure are examples of activities.

activity threshold

A threshold that applies to an individual activity. If an activity exceeds the upper boundary of the threshold tracking that activity, the corresponding action is executed and applied once to that activity. See also aggregate threshold.

adaptive compression

Data row compression that encompasses classic row compression and the compression that is provided by automatically maintained page-level dictionaries. See also classic row compression.

ADC

See automatic dictionary creation.

address space

The range of addresses available to a computer program or process. Address space can refer to physical storage, virtual storage, or both. See also buffer pool.

administration notification log

A list of messages that helps an administrator to resolve minor issues. See also contact.

administration notification message

An alarm, error message, warning, attention message, or informational message that is written by the database manager, replication programs, user applications, or the health monitor to a notification file or event log. See also contact.

administration queue

In Q replication and event publishing, a WebSphere MQ queue that is used by the Q Apply program, Q Capture program, and subscribing applications to communicate.

administrator

A person responsible for administrative tasks such as access authorization and content management. Administrators can also grant levels of authority to users.

after-image

See after-value.

after trigger

A trigger that is specified to be activated after a defined trigger event (an insert, an update, or a delete operation on the table that is specified in a trigger definition). See also before trigger, instead of trigger, trigger, trigger activation, trigger activation time.

after-value

In data replication, the updated value of a source-table column after an SQL insert or update has been applied to the table. See also before-value.

agent

In Q replication, one of the threads of the Q Apply program that is started by the Q Apply browser. It receives transactions from the browser and applies this data to target tables. One or more agents can exist for each browser.
In a z/OS environment, the structure that associates all processes that are involved in a unit of work.
A thread on a server that manages the requests made by an application. See also engine dispatchable unit.

agent private memory

Memory that is allocated for a database agent when the agent is assigned as the result of a connect request or a new SQL request in a parallel environment. The memory is used only by the specific agent. See also private sort.

aggregate function

A function that optionally accepts arguments and returns a single scalar value that is the result of an evaluation of a set of like values, such as those in a column within a set of one or more rows. See also function, routine.

aggregate table

In SQL replication, a read-only replication target table that contains aggregations of data from the source table. This data is based on SQL column functions such as MIN, MAX, SUM, and AVG.

aggregate threshold

A threshold that applies to a group of activities. If an activity in that group exceeds the boundary set by the threshold, the corresponding action is applied to that activity. See also activity threshold.

AIC

See asynchronous index cleanup.

alert

A message or other indication that signals an event or an impending event.
A notice that describes replication events and conditions. The Replication Alert Monitor sends alerts to an email address or to a pager.

alias

An alternative name used to identify a database, a module, a nickname, a sequence, a table, a view, or another alias. An alias can be used in SQL statements to refer to an object in the same DB2 system or subsystem or in a remote DB2 system or subsystem. See also alias chain, database name, public alias, server name.

alias chain

A series of aliases that refer to one another in a sequential, non-repeating fashion; that is, cycles are not allowed. See also alias.

allied thread

A thread that originates at the local DB2 for z/OS subsystem and that can access data at a remote DB2 for z/OS subsystem.

allocated cursor

A cursor that is defined for procedure result sets by using the SQL statement ALLOCATE CURSOR.

American Standard Code for Information Interchange (ASCII)

A standard code used for information exchange among data processing systems, data communication systems, and associated equipment. ASCII uses a coded character set consisting of 7-bit coded characters. See also Extended Binary Coded Decimal Interchange Code.

AMR

See authority mask register.

anchored data type

A data type that is defined to be continuously the same as the data type of the object referenced in the ANCHOR clause.

annotated XML schema

An XML schema composed of XML schema documents that use annotation elements and attributes that are specific to XML document decomposition. An annotated XML schema is used by decomposition procedures to specify the mapping of XML data to database tables and columns.

anti-join

An answer set in which the returned rows do not meet the condition of the join predicate.

AP

See application process.

APF

See authorized program facility.

API

See application programming interface.

application

One or more computer programs or software components that provide a function in direct support of a specific business process or processes. See also application server.

application ID

A unique string that is generated when an application connects to a database or when DB2 Connect receives a request to connect to a Distributed Relational Database Architecture database. This ID is known on both the client and the server and can be used to correlate the two parts of the application.

application period

A pair of columns with application-maintained values that indicates the period of time when a row is valid. See also application-period temporal table.

application-period temporal table

A table that includes an application period. See also application period, bitemporal table.

application plan

The control structure that is produced during the bind process. DB2 for z/OS uses an application plan to execute SQL statements.

application process (AP)

A unit to which resources and locks are allocated. An application process involves the running of one or more programs.

application program

A program used to communicate with stations in a network, enabling users to perform application-oriented activities.

application programming interface (API)

An interface that allows an application program that is written in a high-level language to use specific data or functions of the operating system or another program.

application request

A request issued directly by an external application, such as an OPEN or EXECUTE request. See also request.

application requester

The source of a request to a remote DRDA-enabled relational database management system (RDBMS). See also application server.

application server

The target of a request from an application requester. The database management system (DBMS) at the application server site services the request. See also application requester.

apply

In data replication, to take source table changes and commit them to a target table.

Apply control server

In SQL replication, a database or subsystem that contains the Apply control tables, which store information about registered replication source tables and subscription sets. See also Apply server, control server.

Apply cycle

In SQL replication, the interval of time during which data is replicated from a source table to a target table.

Apply latency

In SQL replication, the approximate time that it takes the Apply program to commit source transactions to target tables after the transactions are made available to the program. See also Capture latency, end-to-end latency, latency, Q Apply latency, Q Capture latency.

Apply program

In SQL replication, a program that is used to refresh or update a replication target table. See also Capture program, Capture trigger, target table.

Apply qualifier

In SQL replication, a case-sensitive character string that identifies replication subscription sets that are unique to an instance of the Apply program.

Apply server

In SQL replication, a system where the Apply program is running. See also Apply control server, control server.

archive log

The set of log files that are closed and are no longer needed for normal processing. These files are retained for use in rollforward recovery. See also active log, circular log.

argument

A value passed to or returned from a function or procedure at run time.

array

A structure that contains an ordered collection of elements of the same data type in which each element can be referenced by its index value or ordinal position in the collection. See also associative array, element, ordinary array.

artifact

An entity that is used or produced by a software development process. Examples of artifacts are models, source files, scripts, and binary executable files.

ASCII

See American Standard Code for Information Interchange.

asensitive cursor

A cursor whose sensitivity is dependent on how an SQL statement is optimized. An asensitive cursor can behave as a sensitive cursor or an insensitive cursor. See also cursor, cursor sensitivity.

associated agent

An agent that has completed work for an application and is available for reassignment to that application if that application must do more work.

associative array

An array with no user-defined upper boundary on the number of elements, which are ordered by and can be referenced by an array index value. Array index values are unique and do not have to be contiguous. See also array, cardinality, element, ordinary array.

asynchronous

Pertaining to events that are not synchronized in time or do not occur in regular or predictable time intervals. See also synchronous.

asynchronous index cleanup (AIC)

An asynchronous task that performs deferred cleanup of indexes following operations that invalidate index entries.

asynchronous I/O

The nonsequential processing of read and write requests across multiple disks.

asynchronous mode

In high availability disaster recovery, the synchronization mode in which the primary database considers a transaction committed when it successfully submits the relevant log data to the network. The primary database does not wait for an acknowledgment that the log data was received by the standby system. See also high availability disaster recovery, peer state, synchronization mode.

asynchronous partition detach

An asynchronous task that makes a logically detached partition into a stand-alone nonpartitioned table. See also logically detached partition.

asynchronous replication

In replication, the process of copying data from a source table to a target table outside the scope of the original transaction that updated the source table. See also synchronous replication.

atomicity

An attribute or property of a transaction whereby a group of statements are run as if a single operation or none of the statements are run.

atomic type

In DB2 XQuery, a data type that can be either a primitive simple data type or a derived type that is based on a primitive simple type. See also atomic value.

atomic value

The smallest obtainable value in an XQuery expression; this atomic type value cannot be deconstructed. See also atomic type, item, XQuery and XPath data model.

atomization

A method of data type conversion that the XQuery language uses to process expressions that expect a sequence of atomic values. Atomization takes a sequence of items and returns the atomic values in the sequence.

attach

To remotely access objects at the instance level.

attached data partition

A data partition that is attached to a table but is not validated using integrity processing. Data in attached data partitions is unavailable to SQL statements. See also visible data partition.

attribute

In markup languages such as SGML, XML, and HTML, a name-value pair within a tagged element that modifies features of the element.
A characteristic or trait of an entity that describes the entity; for example, the telephone number of an employee is one of the employee attributes. See also entity.

audit

To record information about database or instance activity by applications or individuals.

audit facility

A utility that generates a trail of audit records for a series of predefined and monitored database events. See also audit policy.

audit log file

The location of audit records generated from the audit facility.

audit policy

An instance of the audit configuration within a database. Users can define one or more audit policies in a database to define what information is recorded by the DB2 audit facility. See also audit facility.

audit trail

A chronological record of events or transactions. An audit trail is used for examining or reconstructing a sequence of events or transactions, managing security, and recovering lost transactions.

authentication

The process by which a system verifies a user's identity. User authentication is completed by a security facility outside the DB2 database system, often part of the operating system or a separate product.

authentication type

One of a finite number of predefined methods for an instance or subsystem that is used to determine how and where a user is authenticated before being permitted access to the instance or subsystem or to any objects found in that instance or subsystem.

authority level

A user's access and ability to perform high-level database management operations such as maintenance and utility operations. In addition, a user's authority level can implicitly include privileges on database objects. See also authorization, database authority, implicit privilege, load authority, privilege, system authority.

authority mask register (AMR)

A register used with POWER6 processors that defines the current authority to access pages of virtual memory according to their storage protection keys. See also storage protection key.

authorization

The process by which data in the database catalog is used to obtain information about an authenticated user, such as which database operations the user can perform and which data objects the user can access. See also authority level, database authority, privilege.

authorization ID

See authorization identifier.

authorization identifier (authorization ID)

A character string that designates a set of privileges and can be used to verify authority. An authorization ID can represent an object, an individual user, an organizational group, a function, or a database role.

authorization token

A token associated with a transaction.

authorized program facility (APF)

In a z/OS environment, a facility that permits the identification of programs that are authorized to use restricted functions.

autocommit

To automatically commit the current unit of work after each SQL statement.

automatic dictionary creation (ADC)

The process of automatically creating a compression dictionary based on conditions associated with data in a table, XML data stored in an XML storage object, or data in a table space partition. See also compression dictionary.

automatic load

In Q replication, a load process in which the Q Apply program loads data into a target table. The user can specify a load utility or let the Q Apply program choose the best available utility. See also manual load.

automatic maintenance

A process by which a DB2 database system uses user-defined objectives to identify and run required maintenance activities during the next available maintenance window. See also maintenance window.

automatic query rewrite

A process that examines an SQL statement that refers to one or more base tables, and, if appropriate, rewrites the statement so that the query performs better.

automatic rebind

See implicit rebind.
In DB2 for z/OS and DB2 for IBM i, a process by which SQL statements are bound automatically (without a user issuing a command) when an application process begins execution and the bound application plan or package that it requires is not valid. See also rebind.

autonomic

Pertaining to an on-demand operating environment that responds automatically to problems, security threats, and system failures.

autonomic computing

A computing environment with the ability to manage itself and dynamically adapt to change in accordance with business policies and objectives. By sensing and responding to situations that occur, autonomic computing shifts the burden of managing a computing environment from people to technology. An autonomic computing environment is self-configuring, self-healing, self-optimizing, and self-protecting.

autonomous procedure

A procedure that is run within a transaction that is independent of the invoking transaction.

autonomous routine

A routine that is run within a transaction that is independent of the invoking transaction.

autonomous transaction

A transaction with a commit scope that is independent from that of the invoking transaction.

auto-resize

Pertaining to a characteristic of database-managed space (DMS) table spaces and regular and large automatic storage table spaces. The table space expands automatically by extending or acquiring containers, as needed, to increase the table space size until the file systems are full or a user-specified limit is reached.

auxiliary HADR standby database

In an HADR multiple standby system, a standby database that allows only the superAsync synchronization mode. Multiple auxiliary HADR standby databases can be defined in a multiple standby system. See also principal HADR standby database, standby database.

auxiliary standby database

See auxiliary HADR standby database.

auxiliary table

A table that stores columns outside the table in which they are defined. See also base table.

axis

The direction of movement through an instance of the XQuery and XPath data model. The six supported axes are child, parent, self, attribute, descendant, and descendant-or-self.

B

backout: The process of undoing uncommitted changes that an application process has made. A backout might be necessary in the event of a failure on the part of an application process or as a result of a deadlock situation. See also roll back.
backup: A copy of a database or table space that can be stored on a different medium and used to restore the database or table space in the event of failure or damage to the original.
backup pending: The state of a database or table space that prevents an operation from being performed until the database or table space is backed up.
base aggregate table: In SQL replication, a type of replication target table that contains data that is aggregated from a replication source table. See also change aggregate table.
Base Control Program (BCP): A program that provides essential services for the MVS and z/OS operating systems. The program includes functions that manage system resources. These functions include input/output, dispatch units of work, and the z/OS UNIX System Services kernel. See also Multiple Virtual Storage, z/OS.
base table: A table that is created by the SQL CREATE TABLE statement and that holds persistent data. See also auxiliary table, created temporary table, declared temporary table, result table, table, temporary table, view.
basic predicate: A predicate that compares two values.
basic sequential access method (BSAM): An access method for storing or retrieving data blocks in a continuous sequence, using either a sequential access or a direct access device.
batch file: A file that contains instructions that are processed sequentially, as a unit.
BCP: See Base Control Program.
before-image: See before-value.
before trigger: A trigger that is specified to be activated before a defined trigger event (an insert, an update, or a delete operation on the table that is specified in a trigger definition). See also after trigger, instead of trigger, trigger, trigger activation, trigger activation time.
before-value: In data replication, the value of a source-table column before an SQL insert or update has been applied to the table. See also after-value.
begin column: In a system period or an application period, the column that indicates the beginning of the period. See also period.
BID: See block identifier.
bidirectional replication: In Q replication, a replication configuration in which changes that are made to one copy of a table are replicated to a second copy of that table. Changes that are made to the second copy are replicated back to the first copy.
big endian: A format for storage or transmission of binary data in which the most significant value is placed first. See also little endian.
binary string: A sequence of bytes that is not associated with a CCSID. For example, the BLOB data type is a binary string. See also coded character set identifier.
binary XML format: A representation of XML data that uses binary values, an approach that facilitates more efficient storage and exchange.
bind: To convert the output from the DBMS precompiler to a usable control structure, such as an access plan, an application plan, or a package.
bind file: A file that is produced by the precompiler when the PRECOMPILE command or the respective API is used with the BINDFILE option.
bit data: Data with character type CHAR or VARCHAR that is not associated with a coded character set and therefore is never converted.
bitemporal table: A table that is both a system-period temporal table and an application-period temporal table. See also application-period temporal table, system-period temporal table.
block: A set of rows retrieved from a database server that are transmitted as a single result set to satisfy a cursor FETCH request.
block-based I/O: A database manager method of reading contiguous data pages from disk into contiguous portions of memory. See also scattered read.
block fetch: A function of the DB2 database that retrieves (or fetches) a set of rows together. Using a block fetch can significantly reduce the number of messages that are sent across the network. Block fetch applies only to cursors that do not update data. See also blocking.
block identifier (BID): An entry that is stored along with a key value in the leaf node of a block index. This identifier references a particular block in a multidimensional clustering table.
block index: An index that is structured in the same manner as a traditional record identifier (RID) index, except that at the leaf level, keys point to a block identifier (BID) instead of an RID.
blocking: A performance improvement technique that ships multiple rows of data to a database client from a server in response to a single FETCH request. See also block fetch.
block lock: The locking of a block within a multidimensional clustering environment.
block map: A bitmap that contains an array of block states, one for each block in the multidimensional clustering table. Each entry in the array has 8 bits, four of which are used: In use, Load, Constraint pending, and Refresh pending.
block size: The number of pages in a block. It is equal to the extent size.
Blox component: An Alphablox software component that is used to build Java EE-based analytic applications.
BOM: See byte order mark.
Boolean data: In SQL, data that has one of three values: true, false, or null.
Boolean search: A search in which one or more search terms are combined by using operators such as AND, NOT, and OR.
bootstrap data set (BSDS): A VSAM data set that contains name and status information for DB2 for z/OS and relative-byte address-range specifications for all active and archive log data sets. It also contains passwords for the DB2 for z/OS directory and catalog and lists of conditional restart and checkpoint records.
boundary white space: In an XQuery direct element constructor, white space characters that occur by themselves in the boundaries between tags, enclosed expressions, or both tags and enclosed expressions.
broadcast join: A join in which all partitions of a table are sent to all database partitions.
browser: A program that can be used to look at data but not change it.
browser thread: In Q replication, a Q Apply program thread that gets messages from a receive queue and passes the messages to one or more agent threads to be applied to targets.
BSAM: See basic sequential access method.
BSDS: See bootstrap data set.
B-tree index: An index that is arranged as a balanced hierarchy of pages and that minimizes access time by realigning data keys as items are inserted or deleted.
buffer: An area of storage that compensates for the different speeds of data flow or timings of events by temporarily holding a block of data to be processed or written to an I/O device.
buffer pool: An area of memory into which data pages are read and in which they are modified and held during processing. See also address space.
built-in function: A function that is defined by the database manager. See also function, routine, user-defined function.
built-in global variable: A global variable that is defined by the database manager. See also database global variable, global variable, special register, user-defined global variable.
built-in procedure: A procedure that is defined by the database manager. See also external procedure, procedure, routine, SQL procedure, user-defined procedure.
byte order mark (BOM): A marker that consists of a Unicode character code that is placed at the beginning of a data stream, typically in a text file. The marker can be used to indicate the byte order and encoding of the data stream. An example of a byte order mark is the UTF-16BE (big endian) BOM 0xFEFF.
byte reversal: A technique in which numeric data is stored with the least significant byte first. The least significant byte is the lowest byte in a number, located at the far right of a string.

C

CA

See certificate authority.

cache

A buffer that contains frequently accessed instructions and data; it is used to reduce access time.

cache table

In a federated system, a logical table object that is used to cache data from a data source table. A cache table comprises a nickname that identifies the data source table, one or more materialized query tables, and a schedule for replicating the data in each materialized query table.

caching

The process of storing frequently used results from a request to memory for quick retrieval, until it is time to refresh the information. The DB2 database manager provides many forms of caching, such as directory caching, package caching, file system caching, and LDAP caching.

CAF

See call attachment facility.

call

To start a program or procedure, usually by specifying the entry conditions and transferring control to an entry point.

call attachment facility (CAF)

A DB2 for z/OS attachment facility for application programs that run in TSO or z/OS batch. The CAF is an alternative to the DSN command processor and provides greater control over the execution environment.

call level interface (CLI)

An API for database access that provides a standard set of functions to process SQL statements, XQuery expressions, and related services at run time. See also embedded SQL.

callout

The action of bringing a computer program, a routine, or a subroutine into effect.

canonical host name

A host name that is not an alias.

capture

In SQL replication, event publishing, and Q replication, to gather changes from a source database. These changes can come from the DB2 log or journal or from source transactions in a relational database that is not a DB2 database.

Capture control server

In SQL replication, a database or subsystem that contains the Capture control tables, which store information about registered replication source tables. The Capture program runs on the Capture control server.

Capture latency

In SQL replication, an approximate difference between the time that source data was changed and the time that the Capture program made the data available to the Apply program by committing the data to a CD table. Capture latency is a subset of the end-to-end latency in a replication configuration. See also Apply latency, end-to-end latency, latency, Q Apply latency, Q Capture latency.

Capture program

In SQL replication, a program that reads database log or journal records to capture changes that are made to DB2 database source tables and store them in staging tables. See also Apply program, Capture trigger, Q Capture program.

Capture schema

In SQL replication, a name that identifies the control tables that are used by an instance of the Capture program.

Capture trigger

In SQL replication, a mechanism that captures delete, update, or insert operations that are performed on source tables other than DB2 source tables. See also Apply program, Capture program.

cardinality

The number of rows in a database table or the number of elements in an array. See also associative array.

cascade delete

A process by which the DB2 database manager enforces referential constraints by deleting all descendent rows of a deleted parent row.

CASE expression

An expression that is selected based on the evaluation of one or more conditions.

case sensitive

Pertaining to the ability to distinguish between uppercase and lowercase letters.

cast function

A function that is used to convert instances of a source data type into instances of a different target data type. In general, a cast function has the name of the target data type and has one single argument whose type is the source data type. Its return type is the target data type.

castout

The process of writing changed pages from a group buffer pool to disk.

catalog

A collection of tables and views that contains descriptions of objects such as tables, views, and indexes.

catalog node

See catalog partition.

catalog partition

In a partitioned database environment, the database partition where the catalog tables for the database are stored. Each database in a partitioned database environment can have its catalog partition on a different database partition server. The catalog partition for a database is automatically created on the database partition server where the CREATE DATABASE command is run.

catalog table

A table that is automatically created in the DB2 database catalog when a database is created. Catalog tables contain information about a database and its objects. See also catalog view.

catalog view

In DB2 for Linux, UNIX, and Windows, a SYSCAT or SYSSTAT view on the catalog table.
One of a set of views automatically created when a database is created. Catalog views contain information about the database and the objects in that database. Examples of information about the database are definitions of database objects and information about the authority that users have on these objects. See also catalog table.

catchup state

In high availability disaster recovery, a state in which the standby database might not have applied all logged operations that occurred on the primary database. In this state, the standby database retrieves and applies previously generated log data to synchronize with the primary database. There are two types of catchup states: local and remote.

CCD table

See consistent-change-data table.

CCS

See coded character set.

CCSID

See coded character set identifier.

CDB

See communications database.

CDRA

See Character Data Representation Architecture.

CD table

See change-data table.

cell

In a multidimensional clustering table, a unique combination of dimension values. Physically, a cell is made up of blocks of pages whose records all share the same values for each dimension column.

central processor complex (CPC)

A physical collection of hardware that consists of main storage, one or more central processors, timers, and channels.

certificate

In computer security, a digital document that binds a public key to the identity of the certificate owner, thereby enabling the certificate owner to be authenticated. A certificate is issued by a certificate authority and is digitally signed by that authority. See also certificate authority, SSL server authentication.

certificate authority (CA)

A trusted third-party organization or company that issues the digital certificates. The certificate authority typically verifies the identity of the individuals who are granted the unique certificate. See also certificate, Secure Sockets Layer, SSL server authentication.

CF

See coupling facility.
See cluster caching facility.

change aggregate table

In SQL replication, a type of replication target table that contains data aggregations that are based on the contents of a CD table. See also base aggregate table.

change-capture replication

The process of capturing changes that are made to a replication source table and applying them to a replication target table. See also full refresh.

change-data table (CD table)

In SQL replication, a replication table on the Capture control server that contains changed data for a replication source table. See also synchpoint.

character

In a computer system, a member of a set of elements that is used for the representation, organization, or control of data.

character conversion

The process of changing data from one character coding representation to another.

character data

Data that has an associated coding representation that defines how to interpret each specific pattern of bits that are grouped into one or more bytes.

Character Data Representation Architecture (CDRA)

An IBM architecture that defines a set of identifiers, resources, services, and conventions to achieve consistent representation, processing, and interchange of graphic character data in heterogeneous environments.

character entity reference

A character string of the form &#xdddd or &#dddd, where dddd is the hexadecimal or decimal equivalent of the Unicode code point of a character. For example, &#x003E and &#0062 are both character entity references to the > (greater-than) sign.

character set

A defined set of characters with no coded representation assumed that can be recognized by a configured hardware or software system. A character set can be defined by alphabet, language, script, or any combination of these items.

character string

A sequence of bytes that represents bit data, single-byte characters, or a mixture of single-byte and multibyte characters.

character string delimiter

A character that is used to identify the beginning and the end of a character string.

charge-back account

An account used for tracking computing resource usage by business departments or projects. Examples of charge-back accounts are "Marketing Department" or "Summer catalog project."

CHECK clause

In SQL, an extension to the SQL CREATE TABLE and SQL ALTER TABLE statements that specifies a table check constraint.

check condition

A restricted form of search condition used in check constraints.

check constraint

A user-defined constraint that specifies the values that specific columns of a base table can contain. See also constraint.

check integrity

The condition that exists when each row in a table conforms to the check constraints that are defined on that table.

check pending

In DB2 for z/OS, a state into which a table can be put where only limited activity is allowed on the table and constraints are not checked when the table is updated. See also set integrity pending.

checkpoint

A point at which the database manager records internal status information in the log; the recovery process uses this information if the subsystem abnormally terminates.

child activity

An activity that is launched during the processing of another activity, which becomes the parent activity. See also parent activity.

child lock

In explicit hierarchical locking, a lock that is held on a table, a page, a row, or a large object. Each child lock has a parent lock.

CICS

An IBM licensed program that provides online transaction-processing services and management for business applications.

CICS attachment facility

A facility that provides a multithread connection to a DB2 database to allow applications that run in the CICS environment to execute DB2 commands.

CIDF

See control interval definition field.

circular log

A database log in which records are overwritten if they are no longer needed by an active database. See also archive log.

claim

A notification to DB2 for z/OS that an object is being accessed. A claim prevents a drain from occurring until the claim is released, which usually occurs at a commit point. See also drain, logical claim.

class

A description of a set of objects that share the same attributes, operations, methods, relationships, and semantics. A class can use a set of interfaces to specify collections of operations that it provides to its environment. See also object.
In object-oriented design or programming, a model or template that can be used to create objects with a common definition and common properties, operations, and behavior. An object is an instance of a class.
In C++, a user-defined data type. A class data type can contain both data representations (data members) and functions (member functions).

classic row compression

Data row compression that is provided by static, table-level compression dictionaries. See also adaptive compression.

clause

In SQL, a distinct part of a statement in the language structure, such as a SELECT clause or a WHERE clause.

CLDR

See Common Locale Data Repository.

cleanse

To ensure that all values in a data set are consistent and correctly recorded.

CLI

See call level interface.

client

A software program or computer that requests services from a server. See also host, server.

client reroute

A method that allows a client application, upon the loss of communication with a database server and the predefinition of an alternative server, to continue working with the original database server or the alternative server with only minimal interruption of the work.

CLP

See command line processor.

CLR

See common language runtime.

cluster

A collection of complete systems that work together to provide a single, unified computing capability.

cluster caching facility (CF)

A subsystem, typically on a dedicated computer or LPAR, that assists in global locking and group buffer pool management for a DB2 pureScale instance on Linux and AIX operating systems. See also preferred primary cluster caching facility, primary cluster caching facility, secondary cluster caching facility.

clustered index

An index whose sequence of key values closely corresponds to the sequence of rows stored in a table. The degree of correspondence is measured by statistics that are used by the optimizer.

clustering block index

See dimension block index.

clustering index

An index that determines how rows are physically ordered (clustered) in a table space. If a clustering index on a partitioned table is not a partitioning index, the rows are ordered in cluster sequence within each data partition instead of spanning the partitions.

cluster interconnect netname

The IP address or host name of the interconnect used for high-speed communication between members, or between members and cluster caching facilities, in a DB2 instance.

cluster takeover

The process of the DB2 product taking over the ownership of a user-managed GPFS cluster.

coded character set (CCS)

A set of unambiguous rules that establishes a character set and the one-to-one relationships between the characters of the set and their coded representations. See also invariant character set.

coded character set identifier (CCSID)

A 16-bit number that includes a specific set of encoding scheme identifiers, character set identifiers, code page identifiers, and other information that uniquely identifies the coded graphic-character representation. See also binary string.

code page

A particular assignment of code points to graphic characters. Within a given code page, a code point can have only one specific meaning. A code page also identifies how undefined code points are handled. See also code point.

code point

A unique bit pattern that represents a character in a code page. See also code page.

code set

See code page.

cold start

The process of starting a system or program using an initial program load procedure.
The process of starting an existing data replication configuration without regard for prior replication activity, causing reinitialization of all subscriptions.

collating sequence

The sequence in which the characters are ordered for the purpose of sorting, merging, comparing, and processing indexed data sequentially.

collocated join

The result of two tables being joined under one of two conditions. The first condition is where the tables are located in a single-partition database partition group in the same database partition. The second condition is where the tables are in the same database partition group, the number of partitioning columns is the same, the columns are partition compatible, both tables use the same partitioning function, and pairs of the corresponding partitioning key columns participate in the equijoin predicates. See also partition-compatible join.

column

The vertical component of a database table. A column has a name and a particular data type (for example, character, decimal, or integer).

column data

The data in a column of a relational database table or view. The type of the data can be any data type supported by the database manager.

column function

See aggregate function.

column option

In a federated system, a parameter of the CREATE NICKNAME and ALTER NICKNAME statements that describes the values in certain columns of the data source object that a nickname references. This information is added to the global catalog and used by the query optimizer to develop better access plans.

command line processor (CLP)

A text-based interface for entering SQL and XQuery statements and database manager commands.

command recognition character (CRC)

A character that permits a z/OS console operator or an IMS subsystem user to route DB2 commands to specific DB2 for z/OS subsystems.

command scope

The breadth of the impact of a command in a data sharing group. In a data sharing environment, a command can have a group scope or a member scope.

commit

To end a unit of work by releasing locks so that the database changes made by that unit of work can be perceived by other processes. This operation makes the data changes permanent.

commit point

A point in time when data is considered to be consistent.

common language runtime (CLR)

The runtime interpreter for all .NET Framework applications. See also .NET Framework.

Common Locale Data Repository (CLDR)

A standard repository of locale data. This data is used for such tasks as formatting dates, times, time zones, numbers, and currency values and sorting text.

common service area (CSA)

In a z/OS operating system, a part of the common area that contains data areas that can be addressed by all address spaces but is protected during its use by the key of the requester.

common table expression

An expression that defines a result table with a name (a qualified SQL identifier). The expression can be specified as a table name in any FROM clause in the fullselect that follows the WITH clause.

communication buffer exit library

A dynamically loaded, shared library that interacts with the DB2 communication layer and has access to the contents of the unencrypted communication buffers that are received at the server from clients and sent from the server to clients.

communications database (CDB)

A set of tables in the DB2 for z/OS catalog that is used to establish conversations with remote database management systems.

comparison operator

In SQL, a symbol used in comparison expressions to specify a relationship between two values. Comparison operators are = (equal to), <> (not equal to), < (less than), > (greater than), <= (less than or equal to), and >= (greater than or equal to).

compensation

On a federated system, the ability to process a portion of an SQL statement that is not supported by a data source. See also pushdown, query optimizer.

compiled SQL PL

SQL procedure language statements that are compiled into sections within a package. See also inline SQL PL.

complete

A table attribute that indicates that the table contains a row for every primary key value of interest. As a result, a complete source table can be used to perform a refresh of a target table.

complete CCD table

In data replication, a CCD table that initially contains all of the rows from the replication source table or view and any predicates from the source table or view. See also noncomplete CCD table.

complex type

A type that contains elements and can include attributes.

composite block index

An index that contains only dimension key columns and is used to maintain the clustering of data during insert and update activity in a multidimensional clustering (MDC) or insert time clustering (ITC) table. See also dimension block index.

composite key

An ordered set of key columns of the same table.

compound SQL statement

A block of SQL statements that is executed in a single call to the application server.

compression dictionary

The dictionary that is referred to during the process of compression and decompression. In DB2 for z/OS, this dictionary is created from the data in a table space or table space partition. In DB2 for Linux, UNIX, and Windows, this dictionary is created from data in each table partition, data in each table in a database partition, or XML data stored in the XML storage object of a table. A compression dictionary is specific to the table space, table space partition, table, or XML storage object from which it was created. See also automatic dictionary creation.

computed constructor

A constructor that creates element, attribute, document, text, processing-instruction, or comment nodes in which the content of the node is based on enclosed expressions. See also constructor, direct constructor.

concurrency

The shared use of resources by multiple interactive users or application processes at the same time.

condensed

In SQL replication, a table attribute that indicates that the table contains current data rather than a history of changes to the data. A condensed table includes no more than one row for each primary key value in the table. As a result, a condensed table can be used to supply current information for a refresh.

condensed CCD table

In data replication, a CCD table that contains only the most current value for a row and has only one row for each key value. See also consistent-change-data table, noncondensed CCD table.

condition

An expression that can be evaluated as true, false, or unknown. It can be expressed in natural language text, in mathematically formal notation, or in a machine-readable language.
A database object that names an SQL exception or warning, optionally with an associated SQLSTATE, that can be signaled or referenced by a handler in SQL PL. See also module object.

configuration file

A file that contains the values of configuration parameters. See also database configuration file, database manager configuration file.

configuration parameter

A parameter whose value limits or defines the resources that can be used by the database manager or a database. Some configuration parameters are informational and define characteristics about the environment that cannot be changed. See also database configuration parameter.

conflict detection

The process of determining whether a replicated change (an insert, an update, or a delete) is incompatible with some characteristic of a target. An incompatibility exists, for example, if changes were made to both a source and a target before replication occurred. See also master table, replica table.

connection

In data communication, an association established between entities for conveying information. See also SQL connection.

connection concentrator

A mechanism that allows applications to stay connected without any resources being used on the DB2 host server. Thousands of connections can be active while only a few agents are active on the DB2 host server.

connection handle

The data object containing information that is associated with a connection that is managed by DB2 ODBC. This information includes general status information, transaction status information, and diagnostic information. See also statement handle.

connection ID

See connection identifier.

connection identifier (connection ID)

A DB2 for z/OS identifier that is supplied by the attachment facility and that is associated with a specific address space connection.

connection pooling

A process in which an application server or any product that interacts with a database on behalf of applications establishes a finite set of connections to the database and maps requests from the applications to this set of connections. Using these connections reduces the overall connection time for these applications and removes the cost of establishing a database connection from the host.

consistency token

A unique identifier that is generated during precompilation, stored in the application source, and sent to the database when the package is bound. The consistency token is used to ensure the integrity of the shared application information that is stored in the database as a package.

consistent-change-data table (CCD table)

In data replication, a type of replication target table that is used for storing history, auditing data, or staging data. A CCD table can also be a replication source. See also condensed CCD table, external CCD table, internal CCD table, noncondensed CCD table, staging table.

constant

A language element that specifies an unchanging value. Constants are classified as string constants or numeric constants.

constraint

A rule that limits the values that can be inserted, deleted, or updated in a table. See also check constraint, foreign key, informational constraint, primary key, referential constraint, unique constraint, unique key.

constructor

An XQuery expression that creates XML structures within a query. See also computed constructor, constructor function, direct constructor.

constructor function

In XQuery, a constructor where the expression is a function invocation that creates a typed atomic value. See also constructor.

contact

A person whose ID is configured to receive email or pager notifications of DB2 administration messages that are written to the administration notification log. The definition for each contact contains the name and the email or pager address of the person to receive notifications and is stored in the contact list of the system that is specified by the CONTACT_HOST configuration parameter of the DB2 administration server. See also administration notification log, administration notification message, orphaned contact.

container

A data storage location, for example, a file, directory, or device. See also table space.

contention

A situation in which a transaction attempts to lock a row or table that is already locked.

context item

The item in a sequence that is currently being processed in an XQuery expression. See also context node, context position.

context node

A context item that is a node. See also context item.

context position

The position of the context item within the sequence of items. See also context item.

context size

The number of items in the sequence of items that is currently being processed. See also focus.

contracting conversion

A process that occurs when the length of a converted string is smaller than that of the source string. See also expanding conversion.

control flow

In DB2 data warehousing, a graphical model that sequences data flows and mining flows, integrates external commands, programs, and stored procedures, and provides conditional processing logic for a data warehouse application.

control interval definition field (CIDF)

In VSAM, a field located in the 4 bytes at the end of each control interval; it describes the free space, if any, in the control interval.

control message

In Q replication, a message from a Q Apply program or a user application that requests a Q Capture program to activate or deactivate a Q subscription or a publication, invalidate a send queue, or confirm that a target table has been loaded.

CONTROL privilege

The authority to completely control an object, which includes the authority to access, drop, or alter an object and the authority to extend privileges on the object to other users or to revoke their privileges on the object.

control server

In SQL replication, a database server that contains replication control tables for the Capture program, Apply program, or Replication Alert Monitor. See also Apply control server, Apply server, Monitor control server, Q Capture server.

conversation

A connection between two programs over a session that allows them to communicate with each other while processing a transaction. See also session, transaction.

coordinate

A member of an ordered set of N numbers that identifies a position in N-dimensional space. For example, in a two-dimensional map of the Earth, a position can be referenced by two coordinates. The first coordinate identifies the latitude value of the position, and the second coordinate identifies the longitude value of the position.

Coordinated Universal Time (UTC)

The international standard of time that is kept by atomic clocks around the world.

coordinate system

A reference framework that is used to define the positions of points in space in two or three dimensions.

coordinating agent

The agent that is directly responsible for processing requests from and responding to an application. If the connection concentrator is not used, the agent remains associated with the application during the life of the application and initiates subagents that work for the application. See also subagent.

coordinator agent

The agent responsible for accepting and processing application requests on a database connection or an instance attachment.

coordinator node

See coordinator partition.

coordinator partition

The database partition server to which the application originally connected and on which the coordinating agent is located.

coordinator subsection

The subsection of an application that starts other subsections (if any) and returns results to the application.

correlated column

In SQL, a relationship between the value of one column and the value of another column.

correlated reference

A reference to a column of a table or view that is outside a subquery. See also correlated subquery.

correlated subquery

A subquery that contains a correlated reference. See also correlated reference.

correlation ID

See correlation identifier.

correlation identifier (correlation ID)

In DB2 for z/OS, an identifier that is associated with a specific thread. In TSO, the correlation ID is either an authorization identifier or the job name.

correlation name

An identifier specified and used within a single SQL statement as the exposed name for objects such as a table, view, table function reference, nested table expression, or data change table reference. Correlation names are useful in an SQL statement to allow two distinct references to the same base table and to allow an alternative name to be used to represent an object.

cost

The estimated total resource usage that is necessary to run the access plan for a statement (or the elements of a statement). Cost is derived from a combination of processor cost (in number of instructions) and I/O cost (in numbers of seeks and page transfers).

counter

A representation of information that is cumulative up until the sample is taken. The counter counts values that increase, such as the number of deadlocks. Counters are reset when an instance or a database is stopped and restarted. See also gauge.

country/region code

See territory code.

coupling facility (CF)

A special logical partition that provides high-speed caching, list processing, and locking functions in a sysplex.

CPC

See central processor complex.

CPU entitlement

The percentage of CPU resources on a host or LPAR that the WLM dispatcher considers a service class to be entitled to use based on its CPU shares attributes.

CPU limit

The maximum percentage of CPU resources that can be consumed by work executing in a specified service class, regardless of relinquished CPU resources becoming available. This percentage is allocated to each LPAR or physical host where the DB2 database manager is running.

crash recovery

The process of bringing a database back to a consistent and usable state after a failure. See also rollforward recovery, version recovery.

CRC

See command recognition character.

created temporary table

A table whose definition is persistent and shared between sessions but whose data is deleted when the session in which the table was instantiated ends. The data in the table is available only within the session in which the table was instantiated. The table is defined by using the SQL statement CREATE GLOBAL TEMPORARY TABLE. See also base table, declared temporary table, temporary table.

cross-memory linkage

In a z/OS environment, a method for invoking a program in a different address space. The invocation is synchronous with respect to the caller.

cross-system coupling facility (XCF)

A component that provides functions to support cooperation between authorized programs running within a sysplex.

cross-system extended services (XES)

A set of services with which multiple instances of an application or subsystem, running on different systems in a sysplex environment, can implement high-performance, high-availability data sharing by using a coupling facility.

CS

See cursor stability.

CSA

See common service area.

cube

A multidimensional representation of data needed for online analytical processing, multidimensional reporting, or multidimensional planning applications.

cube server

A high-performance, scalable cubing engine that is designed to support queries from many users against many different OLAP cubes.

current data

Data within a host structure that is current with (that is, identical to) the data within the base table.

currently committed

A state that increases the concurrency of read-only data access by allowing the committed version of a row to be processed when a lock is encountered instead of requiring the query to wait for the lock to be released. See also optimistic locking, pessimistic locking.

current path

See SQL path.

current SQL ID

In DB2 for z/OS, an identifier that, at a single point in time, holds the privileges that are exercised when certain dynamic SQL statements run. The current SQL ID can be a primary authorization ID or a secondary authorization ID.

current working directory

See working directory.

cursor

A named control structure used by an application program to point to and select a row of data from a set. See also asensitive cursor, cursor sensitivity, dynamic cursor, insensitive cursor, parameterized cursor, sensitive cursor, static cursor.

cursor blocking

See blocking.

cursor sensitivity

The degree to which database updates made by the same application process or another application process are incorporated in the data returned by FETCH statements for a cursor after the database updates. See also asensitive cursor, cursor, insensitive cursor, sensitive cursor.

cursor stability (CS)

An isolation level under which a query in a transaction is prevented from reading any changes made to rows by statements in other transactions until the changes have been committed. A transaction using CS with an updatable cursor prevents statements in other transactions from changing and possibly reading a row until the cursor has moved from that row. See also isolation level, read stability, repeatable read, uncommitted read.

cursor variable

A global variable, local variable, or parameter of a cursor data type.

D

daemon

A program that runs unattended to perform continuous or periodic functions, such as network control.

data area

A memory area that is used by a program to hold information.

database (DB)

A collection of interrelated or independent data items that are stored together to serve one or more applications. See also database server.

database activity

See activity.

database administrator (DBA)

A person who is responsible for the design, development, operation, maintenance, and use of a database.

database agent

A representation of the physical process or thread that does the work inside the database engine.

database authority

An authority that authorizes the possessor to perform database-level tasks, such as connecting to the database or creating packages in the database. See also authority level, authorization.

database client

A workstation used to access a database that is on a database server.

database configuration file

The configuration file for an individual database. See also configuration file.

database configuration parameter

A parameter whose value limits the system resources that a database can use. See also configuration parameter.

Database Connection Services directory (DCS directory)

A directory that contains entries for remote host databases and the corresponding application requester used to access them.

database directory

A directory that contains database access information for all databases to which a client can connect.

database engine

The part of the database manager that provides the base functions and configuration files that are needed to use the database.

database global variable

A global variable whose value is shared across all sessions in a database. See also built-in global variable, global variable, session global variable, user-defined global variable.

database log

A set of primary and secondary log files consisting of log records that record all changes to a database. The database log is used to roll back changes for units of work that are not committed and to recover a database to a consistent state.

database-managed space table space (DMS table space)

A table space whose storage space is managed by the database manager. See also system-managed space table space.

database management system (DBMS)

A software system that controls the creation, organization, and modification of a database and the access to the data that is stored within it.

database manager

A program that manages data by providing centralized control, data independence, and complex physical structures for efficient access, integrity, recovery, concurrency control, privacy, and security. See also data server.

database manager configuration file

The configuration file for a DB2 instance. See also configuration file.

database manager configuration parameter

A configuration parameter whose value is set when an instance is created. Most database manager configuration parameters affect the amount of system resources that is allocated to a single instance of the database manager, or they configure the setup of the database manager and the different communications subsystems based on environmental considerations.

database manager instance

A logical database manager environment that consists of configuration files, directories, and a set of authorized users.

database name

An identifier that designates a database. A database name must be unique within the location in which it is cataloged. See also alias, server name.

database node

See database partition.

database object

An object that exists in an installation of a database system, such as an instance, a database, a database partition group, a buffer pool, a table, or an index. See also object.

database partition

A portion of the database that contains user data and indexes. There can be multiple database partitions in a partitioned database environment. See also data partition, database partition group, database partitioning, distribution key, table-partitioning key.

database partition group

A named subset of database partitions that is grouped together with a common distribution map. All table spaces that are created under the same database partition group have data on the same set of database partitions. See also database partition.

database partitioning

A data organization scheme in which table data is divided across multiple database partitions based on the hash values in one or more distribution key columns of the table and based on the use of a distribution map of the database partitions. Data from a given table is distributed based on the specifications that are provided in the DISTRIBUTE BY clause of the CREATE TABLE statement. See also data partition, database partition, massively parallel processing, table partitioning.

database recovery log

See database log.

database request

See request.

database server

A software program that uses a database manager to provide database services to other software programs or computers. See also database.

database system monitor

A collection of APIs that gathers information regarding the state of the database system at the instance, database, and application levels. This information is stored in data elements, which can be examined by taking point-in-time snapshots or by using the event monitor to log system activity over time.

Data Definition Language (DDL)

A language for describing data and its relationships in a database. See also Data Manipulation Language.

data definition name (ddname)

The name of a data definition (DD) statement that corresponds to a data control block that contains the same name.

Data Description Language

See Data Definition Language.

data element

See monitor element.

Data Facility Product (DFP)

A program that isolates applications from storage devices, storage management, and storage device hierarchy management.

data flow

A graphical model that defines activities that extract data from flat files or relational tables, transform the data, and load it into a data warehouse, data mart, or staging table.

data interchange

The sharing of data between applications.

Data Management Services

The DB2 component that controls creating, removing, maintaining, and accessing the tables and table data in a database.

Data Manipulation Language (DML)

A subset of SQL statements that is used to manipulate data. Most applications primarily use DML SQL statements, which are supported by the DB2 Connect program. SELECT, INSERT, UPDATE, and DELETE statements are similar across the IBM relational database products. See also Data Definition Language, Structured Query Language.

data mart

A subset of a data warehouse that contains data that is tailored and optimized for the specific reporting needs of a department or team. A data mart can be a subset of a warehouse for an entire organization, such as data that is contained in online analytical processing (OLAP) tools.

data message

In Q replication and event publishing, a message that contains all or part of a committed transaction that involves source tables, a committed operation on a single row in a source table (event publishing only), or all or part of a large object (LOB) value from a row operation within a transaction.

data mining

The process of collecting critical business information from a data warehouse, correlating the information and uncovering associations, patterns, and trends.

data movement operation

An operation that physically moves a row from one location to another location in a table. Examples of data movement operations are updating database partitioning keys and reorganizing tables.

data partition

A set of table rows that is stored separately from other sets of rows. A data partition is grouped by the specifications that are provided in the PARTITION BY clause of the CREATE TABLE statement. See also database partition, database partitioning, table partitioning, table-partitioning key.

data server

A server that provides services for the secure and efficient management of information. See also database manager.

data server client

See IBM data server client.

Data Server Client

See IBM Data Server Client.

data server driver copy

See IBM data server driver copy.

Data Server Provider for .NET

See IBM Data Server Provider for .NET.

data sharing

The ability of subsystems or application programs to access data directly and to change it while maintaining data integrity.

data sharing group

A collection of one or more systems that directly access and change the same data while maintaining data integrity.

data-sharing instance

See DB2 pureScale instance.

data sharing member

A local or remote relational or nonrelational data manager that can support data access using an ODBC driver that supports the ODBC APIs.

data skew

The uneven distribution of data values across logical or physical data storage media.

data source

A repository of data to which a federated server can connect and then retrieve data by using wrappers. A data source can contain relational databases, XML files, Excel spreadsheets, table-structured files, or other objects. In a federated system, data sources seem to be a single collective database.

data source object

In a federated system, an object at a remote data source on which operations can be performed. Examples of data source objects are tables, views, synonyms, table-structured files, and Excel spreadsheets. See also nickname.

data tag

A user-defined numeric value that uniquely identifies a group of data. Data tags can be assigned to table spaces or storage groups and are used in DB2 workload management configurations to monitor and control activities based on which data the activities access.

data type

In SQL, a descriptor of a set of values and a set of permitted operations. A data type determines the kind of value that a column, literal, parameter, special register, or variable can have or that can be the result of an expression, a function, or a method.

data type mapping

The mapping of a data type to another data type across products or languages. For example, the Oracle type FLOAT maps to the DB2 type DOUBLE. See also forward data type mapping, reverse data type mapping.

data warehouse

A subject-oriented collection of data that is used to support strategic decision making. The warehouse is the central point of data integration for business intelligence. It is the source of data for data marts within an enterprise and delivers a common view of enterprise data.

date

A three-part value that designates a day, month, and year: for example, YYYY-MM-DD. See also timestamp.

date duration

A DECIMAL(8,0) value that represents a number of years, months, and days in the format yyyymmdd.

datetime value

A value of the data type DATE, TIME, or TIMESTAMP.

DB

See database.

DB2 administration server

A control point that is used to assist with administration tasks on DB2 servers and to perform remote tasks on the server and the host system on behalf of a client request. The DB2 administration server is deprecated.

DB2 Call Level Interface

See call level interface.

DB2 client

See IBM data server client.

DB2 cluster services

The software components that the DB2 pureScale Feature uses for recovery automation, cluster management, and shared storage in a DB2 pureScale instance.

DB2 cluster services tiebreaker

A shared disk partition that helps determine which group of hosts in the DB2 pureScale instance has the operational quorum and survives if the InfiniBand network encounters a split instance due to a communication failure.

DB2 command

An instruction to the operating system to access and maintain the database manager. For example, DB2 commands can be used to start or stop a database and to display information about current users and the status of databases.

DB2 control server

A DB2 database system that contains the satellite control database, SATCTLDB. See also satellite.

DB2 copy

One or more installations of DB2 database products in a particular location on a system. Multiple DB2 copies can be installed and run on the same system.

DB2 copy name

The name that refers to a single instance of an installation of a DB2 database product, which is specified when the product is installed.

DB2I

See DB2 Interactive.

DB2 Interactive (DB2I)

An interactive service within DB2 for z/OS that facilitates the execution of SQL statements, DB2 operator commands, and programmer commands and the invocation of utilities.

DB2 member

See member.

DB2 Net Search Extender

A program that provides full-text retrieval through a DB2 procedure.

DB2 notify log

See administration notification log.

DB2 pureScale instance

A DB2 instance that uses the DB2 pureScale architecture and runs on multiple hosts.

DB2 Spatial Extender

A DB2 component that stores and manipulates spatial data. DB2 Spatial Extender is used to generate and analyze spatial information about geographic features.

DB2 Text Search

A component that can be optionally installed with DB2 Database for Linux, UNIX, and Windows that provides text search capabilities. DB2 Text Search works with SQL, XML, and XQuery.

DB2 WLM

See DB2 workload manager.

DB2 workload management

The DB2 capability that monitors and controls the flow of work and resource consumption, including the capability in the DB2 workload manager.

DB2 workload manager (DB2 WLM)

The subset of DB2 workload management capability that can be used to create a DB2 workload, a DB2 service class, a DB2 threshold, or a DB2 work action set. This subset of capability is controlled by a separate license.

DBA

See database administrator.

DBCS

See double-byte character set.

DBMS

See database management system.

DCS directory

See Database Connection Services directory.

DDF

See distributed data facility.
See Dynamic Data Format.

DDL

See Data Definition Language.

ddname

See data definition name.

deadlock

Unresolved contention for the use of resources.

deadlock detector

A process within the database manager that monitors the states of the locks to determine whether a deadlock condition exists. When a deadlock condition is detected, the detector stops one of the transactions involved in the deadlock. This transaction is rolled back, and the other transaction can proceed.

decimal floating-point number

A 64-bit or 128-bit representation of a number with a precision of 16 or 34 decimal digits and an exponent. Decimal floating-point numbers include normal numbers, subnormal numbers, and the special values of infinity, NaN, and sNaN. In IBM SQL, decimal floating-point numbers are not considered to be floating-point numbers. See also floating-point number, infinity, normal number, not-a-number, signaling NaN, subnormal number.

declared procedure

The object resulting from processing a DECLARE PROCEDURE statement in a compiled compound statement.

declared temporary table

A table that holds temporary data and is defined by using the SQL statement DECLARE GLOBAL TEMPORARY TABLE. Information about declared temporary tables is not stored in the DB2 catalog, so this kind of table is not persistent and can be used only by the application process that issued the DECLARE statement. See also base table, created temporary table, temporary table.

decomposition

The process of breaking up an XML document for storage in database tables.

default database client interface copy

See default IBM database client interface copy.

default DB2 copy

The DB2 copy that is used by applications that access DB2 database products through the default interface. Multiple DB2 copies can be installed and run on the same system.

default IBM database client interface copy (default database client interface copy)

The copy that applications requiring the use of the IBM Data Server Driver for ODBC and CLI and the IBM Data Server Provider for .NET use by default.

default interface

An interface with a well-known name that applications specify when using DB2 databases.

default namespace

The namespace that is applied if an XML element, type, or function has no namespace prefix. If the URI reference in a default namespace declaration is empty, unprefixed elements in the scope of the declaration are not considered to be in any namespace.

default subsystem name (DSN)

The name of the DB2 subsystem that can connect to the control server (the default subsystem name is DSN).

deferred embedded SQL

SQL statements that are neither fully static nor fully dynamic. Like static statements, they are embedded within an application, but like dynamic statements, they are prepared during the execution of an application. See also dynamic SQL, incremental bind statement, static SQL.

deferred index cleanup rollout

A rollout in which index cleanup is performed after the deletion of the portion of the MDC table is complete. Deferred index cleanup rollout is significantly faster than immediate index cleanup rollout, but rolled-out blocks are not available for immediate reuse. See also rollout.

deferred write

The process of asynchronously writing changed data pages to disk.

degree of parallelism

The number of concurrently executed operations that are initiated to process a query.

delete-connected

In SQL, a property of a table that is a dependent of table P or a dependent of a table to which delete operations from table P cascade.

delete hole

A row in the result of a SELECT statement of a cursor that no longer has a corresponding row in the base table because that row was deleted. The row for the SELECT statement is no longer accessible though the cursor. See also hole, update hole.

delete rule

A rule associated with a referential constraint that either restricts the deletion of a parent row or specifies the effect of such a deletion on the dependent rows.

delete trigger

A trigger that is activated by a delete operation on the table or view that is specified in the trigger definition. See also insert trigger, instead of trigger, trigger, update trigger.

delimited identifier

A sequence of one or more characters enclosed by quotation marks ("").

delimiter

A flag that is formed by a character or a sequence of characters to group or separate items of data by marking the beginning and end of a unit of data. The delimiter is not a part of the flagged unit of data.

delimiter token

A string constant, a delimited identifier, an operator symbol, or any of the special characters shown in syntax diagrams.

delta backup

A copy of all database data that has changed since the last successful backup (full, incremental, or delta) of the table space in question. A delta backup is also known as a differential, or noncumulative, backup image. The predecessor of a delta backup image is the most recent successful backup that contains a copy of each of the table spaces in the delta backup image.

denormalization

The intentional duplication of columns in multiple tables to increase data redundancy. Denormalization is sometimes used to improve performance. See also normalization.

dependent

In SQL, an object (row, table, or table space) that has at least one parent. See also parent table space.

dependent foreign key table

A foreign key table that is a dependent in at least one referential constraint. See also descendent foreign key table, parent table.

dependent immediate materialized query table

A table whose definition is based on the result of a query and whose data is in the form of precomputed results. These results come from the tables or nicknames that are used in the definition of the materialized query table.

dependent materialized query table

A materialized query table that is dependent on a given table.

dependent row

A row that contains a foreign key that matches the value of a parent key in the parent row. The foreign key value represents a reference from the dependent row to the parent row. See also parent row.

dependent staging table

The staging table for a dependent materialized query table of a given table.

dependent table

A table that is a dependent of an object. For example, a table with a foreign key is a dependent of the table containing the corresponding primary key. See also descendent table, parent table.

deprecated

Pertaining to an entity, such as a programming element or feature, that is supported but no longer recommended and that might become obsolete.

descendent

An object that is a dependent of another object or is a dependent of an object that is in turn a dependent of another object.

descendent foreign key table

A dependent foreign key table of a descendent foreign key table of a given table. See also dependent foreign key table.
A dependent foreign key table of a given table.

descendent immediate materialized query table

A descendent materialized query table that is defined with the REFRESH IMMEDIATE option.

descendent materialized query table

A dependent materialized query table of a descendent foreign key table of a given table.
A dependent materialized query table of a given table.

descendent row

A row that is a dependent of another row or is a descendent of a dependent of another row.

descendent staging table

A dependent staging table of a given table.
A dependent staging table of a descendent foreign key table of a given table.

descendent table

A table that has a dependent relationship on a parent table or on another descendent table. See also dependent table.

detached data partition

A data partition that is detached from a table but remains part of the table pending the completion of asynchronous index cleanup or integrity processing on dependent tables. Data in detached data partitions is unavailable to SQL statements. See also visible data partition.

detached dependent table

A dependent table that must be incrementally maintained after a data partition is detached using an ALTER TABLE statement.

detached table

A table, created from a detached data partition by using an ALTER TABLE statement, that is inaccessible until all of the corresponding detached dependent tables are maintained.

deterministic function

A user-defined function with a result that is dependent on the values of the input arguments. Successive invocations with the same input values produce the same answer.

device name

A name reserved by the system or a device driver that refers to a specific device. For example, the DOS device name for the parallel port is LPT1.

DFP

See Data Facility Product.

differential refresh

See change-capture replication.

dimension

A data category that is used to organize and select monitoring context instances for reporting and analysis. Examples of dimensions are time, accounts, products, and markets. See also member.
In multidimensional data, a structural attribute of a cube that organizes data to enable in-depth business analysis.

dimension block index

In multidimensional clustering, a block index that is automatically created for a particular dimension when the dimension is defined on an MDC table. This index is used to maintain the clustering of data along that dimension, together with the other dimensions defined on the table. See also composite block index.

dimension table

The representation of a dimension in a star schema. Each row in a dimension table represents all of the attributes for a particular member of the dimension. See also star join, star schema.

direct constructor

An XQuery constructor that contains XML-like notation to construct element, attribute, document, text, processing-instruction, or comment nodes. See also computed constructor, constructor.

directed join

A relational operation in which all of the rows in one or both of the joined tables are rehashed and directed to new database partitions based on the join predicate. If all of the partitioning key columns in one table participate in the equijoin predicates, the other table is rehashed; otherwise (if there is at least one equijoin predicate), both tables are rehashed.

directory

The DB2 for z/OS system database that contains internal objects such as database descriptors and skeleton cursor tables.

disaster recovery

The process of restoring a database after a partial or complete site failure that was caused by a catastrophic event such as an earthquake or fire. Typically, disaster recovery requires a full database backup at another location.

dispatch concurrency level

The number of threads that the WLM dispatcher can dispatch to the operating system at the same time.

distinct type

A user-defined data type that shares a common representation with a built-in data type. See also strongly typed distinct type, weakly typed distinct type.

distributed data facility (DDF)

A set of DB2 for z/OS components through which DB2 for z/OS communicates with another RDBMS.

distributed relational database

A database whose tables are stored on different but interconnected computing systems.

Distributed Relational Database Architecture (DRDA)

The architecture that defines formats and protocols for providing transparent access to remote data. DRDA defines two types of functions: the application requester function and the application server function.

distributed request

In a federated system, an SQL query directed to two or more data sources.

distributed transaction

A transaction that updates data in more than one database, user process, or machine. See also two-phase commit, XA.

distributed unit of work (DUOW)

A unit of work that allows SQL statements to be submitted to multiple relational database management systems, but no more than one system per SQL statement.

distribution array

An arrangement of entries that indicates the number of records that are hashed into a hash index. See also distribution file.

distribution file

A file that stores a distribution array. See also distribution array.

distribution key

An ordered set of one or more columns in a table. The values in the distribution key columns are used to determine the database partition to which each table row belongs. See also database partition, table-partitioning key.

distribution map

A map that specifies an array of database partition numbers that is used to distribute data among the database partitions of a database partition group. The array of database partition numbers distributes the data by using a hashing algorithm.

distribution summary array

An array that includes a distribution array and a distribution map and that indicates the number of records that are hashed into a database partition.

DML

See Data Manipulation Language.

DMS table space

See database-managed space table space.

DNS

See domain name server.

document model

The definition of the structure of a document in terms of the sections that it contains. DB2 Net Search Extender uses a document model when indexing.

document order

In XQuery, an ordering among the nodes in a node hierarchy that corresponds to the order in which the nodes would appear if the node hierarchy were serialized in XML format.

document type definition (DTD)

The rules that specify the structure for a particular class of SGML or XML documents. The DTD defines the structure with elements, attributes, and notations, and it establishes constraints for how each element, attribute, and notation can be used within the particular class of documents.

domain

A part of a network that is administered as a unit with a common protocol.

domain name

In Internet communications, a name of a host system. A domain name consists of a sequence of subnames that are separated by a delimiter character, for example, www.ibm.com.

domain name server (DNS)

A server program that supplies name-to-address conversion by mapping domain names to IP addresses.

double-byte character set (DBCS)

A set of characters in which each character is represented by 2 bytes. These character sets are commonly used by national languages, such as Japanese and Chinese, that have more symbols than can be represented by a single byte. See also multibyte character set, single-byte character set.

double-precision floating-point number

A 64-bit approximate representation of a real number. See also floating-point number.

drain

The act of acquiring a locked resource by quiescing access to that object. See also claim, logical drain.

DRDA

See Distributed Relational Database Architecture.

DSN

See default subsystem name.

DTD

See document type definition.

dump

A capture of storage information at the time of an error.
To record or copy, at a particular instant, data from one storage device onto another storage device to protect the data and debug the program.

DUOW

See distributed unit of work.

duration

In SQL, a number that represents an interval of time.

dynamic context

The information that is available at the time that an XQuery expression is evaluated. The dynamic context consists of all of the components of the static context, plus additional components such as the context item, context position, and context size. See also expression context, static context.

dynamic cursor

A named control structure that an application program uses to change the size of the result table and the order of its rows after the cursor is opened. See also cursor, static cursor.

Dynamic Data Format (DDF)

A format used to package LOB or XML values sent by a database server, capable of holding the actual value, a reference to the value following later in the stream of data, or a token representing the value for later retrieval. See also progressive streaming.

dynamic IP address

A temporary IP address for a transient device or logical unit on a network: for example, a personal computer. See also IP address.

dynamic SQL

An SQL statement that is prepared and executed at run time. In dynamic SQL, the SQL statement is contained as a character string in a host variable and is not precompiled. See also deferred embedded SQL, incremental bind statement, static SQL.

E

EBCDIC

See Extended Binary Coded Decimal Interchange Code.

EBV

See effective Boolean value.

EDU

See engine dispatchable unit.

effective Boolean value (EBV)

The result of converting a sequence of items into a logical value of true or false.

elapsed time

For a thread or an agent, the total time spent within a monitored time interval. See also processing time.

element

In markup languages, a basic unit consisting of a start tag, end tag, associated attributes and their values, and any text that is contained between the two.
An entity that satisfies all of the conditions of belonging to a given set. For example, an element within an array can be accessed by using the array index. See also array, associative array, ordinary array.
A value in a security label component. See also security label component.

ELT

See extract, load, and transform.

embedded SQL

An SQL statement that is coded within an application program. See also call level interface, static SQL.

encoding scheme

A set of rules to represent character data.

encryption

In computer security, the process of transforming data into an unintelligible form in such a way that the original data either cannot be obtained or can be obtained only by using a decryption process.

end column

In a system period or an application period, the column that indicates the end of the period. See also period.

end of memory (EOM)

The outer boundary of an address space.

end-to-end latency

In SQL replication, an approximate measurement of the difference between the time that a change takes place in a source table and the time that the change is applied to a target table. See also Apply latency, Capture latency, latency, Q Apply latency, Q Capture latency, queue latency.

engine dispatchable unit (EDU)

A DB2 structure that coordinates application requests to a DB2 database by using a process (on UNIX operating systems) or a thread (on Windows operating systems) to carry out instructions on behalf of the DB2 database system. See also agent.

enhanced conflict detection

In SQL replication, conflict detection that guarantees data integrity among all replicas and the source table. The Apply program locks all replicas or user tables in the subscription set against further transactions. It begins detection after all changes made before locking have been captured.

entity

A person, object, or concept about which information is stored.

entry-sequenced data set (ESDS)

A VSAM data set whose records are physically in the same order in which they were put in the data set. A VSAM data set is processed by using addressed direct access or addressed sequential access and has no index. New records are added at the end of the data set.

environment handle

A handle that identifies the global context for database access. All data that is pertinent to all objects in the environment is associated with this handle.

environment variable

A variable that defines an aspect of the operating environment for a process. For example, environment variables can define the home directory, the command search path, the terminal in use, or the current time zone.
A variable that is included in the current software environment and is therefore available to any called program that requests it.

EOM

See end of memory.

equijoin

A join whose join condition uses only the equals predicate. See also join.

error page range

A range of pages that are considered to be physically damaged.

ESC

See escape character.

escape character (ESC)

A symbol that is used to modify the interpretation of the character or characters that follow it. Examples of uses of escape characters in SQL are delimiting identifiers, delimiting character constants, and modifying the special meaning of the underscore (_) and percent (%) characters in the LIKE predicate.
A character that suppresses or selects a special meaning for one or more characters that follow.

ESDS

See entry-sequenced data set.

ETL

See extract, transform, and load.

EUC encoding scheme

See Extended UNIX Code encoding scheme.

event

A transition in database activity caused by users, applications, or the database manager. Events include connections, deadlocks, and transactions. See also event monitor.

event monitor

A database object for monitoring and collecting data on database activities over time. For example, starting the database might be an event that causes an event monitor to track the number of users on the system by taking an hourly snapshot of authorization IDs using the database. See also event, unformatted event table.

event publishing

A data publishing solution that captures changed data and publishes it to subscribing applications. See also publishing queue map, Q Capture program.

exception table

A table that holds rows that violate referential constraints or check constraints that the CHECK DATA utility finds.
A user-created table that reflects the definition of the table being loaded.

exchange station ID (XID)

In communications, a data link command or response for recognizing the primary station and a secondary station.

exclusive connection

A connection that gives one user sole access to a particular database so that database operations are restricted to that user. The user with the exclusive connection can establish additional connections in shared mode.

exclusive lock

A lock that prevents concurrently executing application processes from accessing database data. See also gross lock, shared lock.

exclusive SQL statement

An SQL statement that must be followed by a commit or rollback operation before any other SQL statement can be executed in the same SQL session. Exclusive SQL statements are grouped into sets; the database manager can execute only one SQL statement from the set at one time. Examples of exclusive SQL statements include the CREATE SERVICE CLASS SQL statement and the AUDIT SQL statement.

executable ID

See executable identifier.

executable identifier (executable ID)

A binary token that uniquely identifies a section.

executable statement

An SQL statement or XQuery expression that can be embedded in an application program, dynamically prepared and executed, or issued interactively.

execution time

The period when a request that is specified by an SQL statement is acted on by a database. See also system time.

exemption

In label-based access control, a privilege that causes one LBAC rule of one security policy to be bypassed for a user or a set of users to whom that privilege is granted. See also LBAC credentials.

exit routine

A program that receives control from another program to perform specific functions.

expanded QName

A QName where the prefix from the lexical form is resolved into the namespace URI. If the lexical form of the QName does not have a prefix, the namespace URI is the default namespace, which can be empty. See also qualified name.

expanding conversion

A process that occurs when the length of a converted string is greater than that of a source string. See also contracting conversion.

explain

To capture detailed information about the access plan that was chosen by the SQL and XQuery compiler to resolve an SQL or XQuery statement. The information describes the decision criteria that are used to choose the access plan.

explainable statement

An SQL or XQuery statement for which the explain operation can be performed. SELECT, UPDATE, INSERT, DELETE, and VALUES are explainable SQL statements.

explained statement

An SQL or XQuery statement for which an explain operation was performed.

explain snapshot

A collection of information that is compressed when an SQL or XQuery statement is explained.

explain statistics

The statistics in the catalog that are referenced when an SQL or XQuery statement is explained.

explicit connection

A connection to a database in which both a user ID and password are specified.

explicit privilege

A privilege that has a name and is held as the result of SQL GRANT and REVOKE statements: for example, the SELECT privilege. See also implicit privilege.

explicit rebind

A process by which SQL statements are bound by a user issuing the REBIND or db2rbind command. See also rebind.

explicit trusted connection

A trusted connection that allows both switching the current user ID of the connection to a different user ID and acquiring a trusted context role (a default or user-specific role). See also trusted connection.

export

To copy data from database manager tables to a file using formats such as PC/IXF, DEL, and ASC. See also import.

exposed name

A name specified in a FROM clause such that it can be referenced elsewhere in the query. Exposed names include correlation names and, if correlation names are not specified for them, table names, view names, nicknames, and alias names. See also table designator.

expression

An SQL or XQuery operand or a collection of SQL or XQuery operators and operands that yields a single value.

expression context

All of the information that can affect the result of a specific XQuery expression. This information is organized into two categories called the static context and the dynamic context. See also dynamic context, static context.

Extended Binary Coded Decimal Interchange Code (EBCDIC)

A coded character set of 256 8-bit characters developed for the representation of textual data. See also American Standard Code for Information Interchange.

extended indicator variable

A variable that is used with a host variable to represent the SQL null value, the default value, or the unassigned value in an application program. See also indicator variable.

extended recovery facility (XRF)

A facility that minimizes the effect of failures in z/OS, VTAM, the host processor, or high-availability applications during sessions between high-availability applications and designated terminals. This facility provides an alternative subsystem to take over sessions from the failing subsystem.

Extended UNIX Code encoding scheme (EUC encoding scheme)

An encoding scheme that defines a set of encoding rules that can support one to four character sets. The encoding rules are based on the ISO2002 definition for the encoding of 7-bit and 8-bit data. The EUC encoding scheme uses control characters to identify some of the character sets.

Extensible Markup Language (XML)

A standard metalanguage for defining markup languages that is based on Standard Generalized Markup Language (SGML).

Extensible Stylesheet Language (XSL)

A language for specifying style sheets for XML documents. Extensible Stylesheet Language Transformation (XSLT) is used with XSL to describe how an XML document is transformed into another document.

Extensible Stylesheet Language Transformation (XSLT)

An XML processing language that is used to convert an XML document into another document in XML, PDF, HTML, or other format.

extent

An allocation of space, within a container of a table space, to a single database object. This allocation consists of multiple pages.

extent map

A metadata structure stored within a table space that records the allocation of extents to each object in the table space.

extent size

In a table space, the number of pages of table data that are written to a container before data is written to the next container.

external CCD table

In SQL replication, a CCD table that can be subscribed to directly because it is a registered replication source. It has its own row in the register table, where it is referenced as SOURCE_OWNER and SOURCE_TABLE. See also consistent-change-data table, internal CCD table.

external entity

In XML, an entity such as an XML schema, an Extensible Stylesheet Language (XSL) style sheet, a document type definition (DTD), or other XML instance document that is accessed using a Uniform Resource Identifier (URI) in an XML instance document. This URI is required to validate the instance document.

external function

A function that has its functional logic implemented in a programming language application that is outside the database, in the file system of the database server. The association of the function with the external code application is specified by the EXTERNAL clause in the CREATE FUNCTION statement. See also external routine, function, user-defined function.

external method

A method that has its method logic implemented in a programming language application that is outside the database, in the file system of the database server. The association of the method with the external code application is specified by the EXTERNAL clause in the CREATE METHOD statement. See also external routine, method.

external name

The name of an executable library or class file that is on the database server and contains the logic for an external routine (an external procedure, external function, or external method).

external procedure

A procedure that has its procedural logic implemented in an external programming language application. The association of the procedure with the external application is specified by a CREATE PROCEDURE statement with a LANGUAGE clause that has a value other than SQL and an EXTERNAL clause that implicitly or explicitly specifies the name of the external application. See also built-in procedure, external routine, procedure, user-defined procedure.

external routine

A function, method, or procedure that has its routine logic implemented in a programming language application that is outside the database, in the file system of the database server. The association of the routine with the external code application is specified by the EXTERNAL clause in the CREATE statement for the routine. See also external function, external method, external procedure, routine.

extract, load, and transform (ELT)

The process of extracting data from one or more sources, loading it directly into a relational database, and then using the database engine to run data transformations. See also extract, transform, and load.

extract, transform, and load (ETL)

The process of collecting data from one or more sources, cleansing and transforming it, and then loading it into a database. See also extract, load, and transform.

extract control file

A file that contains statements that control the operation of an extractor utility program.

F

fabricated statistics

Statistics that are created or derived instead of collected by using the RUNSTATS command. For example, the number of rows in a table can be derived from the number of pages, the page size, and the average row width in the table. Fabricated statistics are used during query compilation.

fact table

A relational table that contains facts, such as units sold or cost of goods, and foreign keys that link the fact table to each dimension table. See also star join.

failback

In high availability disaster recovery, the process of restarting the original primary system and returning it to its status of primary system after a failover has occurred.

failover

An automatic operation that switches to a redundant or standby system in the event of a software, hardware, or network interruption. See also failback.

fallback

The process of automatically switching back to the original database server after failure caused a switch to an alternative database server.

false negative

A condition when using optimistic locking whereby a row that was not updated since it was selected cannot be updated without first being selected again. Optimistic locking support does not allow a false positive to happen, but a false negative might happen. See also false positive.

false positive

A condition when using optimistic locking whereby a row that was updated since it was selected is updated without first being selected again. Optimistic locking support does not allow a false positive to happen, but a false negative might happen. See also false negative.

fast communication manager (FCM)

A group of functions that provides internodal communication support.

FAT

See file allocation table.

fault monitor

A daemon process that monitors DB2 instances and can restart stopped instances.

FCM

See fast communication manager.

federated database

In a federated system, the database that is within the federated server. Users and applications interface with the federated database. To these clients, the data sources and the federated database seem to be a single database.

federated procedure

A federated database object that references a procedure on a data source.

federated server

The DB2 server in a federated system. Existing DB2 instances can be used as a federated server, or new instances can be created specifically for the federated system.

federated system

A distributed database management system (DBMS) that consists of a DB2 instance that operates as a server, a database that serves as the federated database, one or more data sources, and clients (users and applications) who access the database and data sources. A federated system can be used to query and manipulate data that is located on other data servers.

fenced

Pertaining to a type, or characteristic, of a procedure, user-defined function, or federated wrapper that is defined to run in a separate process from the database manager. When a fenced object runs in fenced mode, the database manager is protected from modifications by the object. See also not fenced, trusted.

fetch

An SQL action that positions a cursor on the next row of its result table and assigns the values of that row to host variables.

fetch orientation

The specification of the placement of the cursor as part of a FETCH statement, for example, BEFORE or AFTER. See also scrollability.

field

In the context of an SQL row data type, a named element of a row that contains data of a particular type.

fielded search

A query that is restricted to a particular field.

field procedure

A user-written exit routine that receives a single value and encodes or decodes it as specified by the user.

file allocation table (FAT)

A table that is used to allocate space on a disk for a file and to locate the file.

file reference variable

A host variable that indicates that data is in a file on the client rather than in a client memory buffer.

filter factor

A number between zero and one that estimates the proportion of rows in a table for which a predicate is true.

first occurrence data capture (FODC)

The process of capturing scenario-based data about a DB2 instance. FODC can be invoked manually by a DB2 user based on a particular symptom or automatically when a predetermined scenario or symptom is detected.

fixed-length string

A character, graphic, or binary string whose length is specified and cannot be changed. See also varying-length string.

flagger

A precompiler option that identifies SQL statements in applications that do not conform to selected validation criteria (for example, the ISO/ANSI SQL92 entry-level standard).

floating-point number

Either a 32-bit or 64-bit approximate representation of a real number. In IBM SQL, floating-point numbers do not include decimal floating-point numbers. See also decimal floating-point number, double-precision floating-point number, single-precision floating point number.

FLWOR expression

An XQuery expression that is comparable to an SQL SELECT statement, providing the capabilities to iterate over input sequences (FOR), bind variables (LET), define filters (WHERE), order filtered results (ORDER BY), and return results (RETURN).

focus

The first three components of the dynamic context (context item, context position, and context size) of an XQuery expression. The focus enables the processor to track which items the expression is processing. See also context size.

FODC

See first occurrence data capture.

foreign key

A column or set of columns that refers to a parent key.
In a relational database, a key in one table that references the primary key in another table. See also constraint, primary key, unique key.

forward data type mapping

In a federated system, the mapping of a data type at a remote data source to a comparable DB2 data type. For most data sources, the default forward data type mappings are in the wrappers. See also data type mapping, reverse data type mapping.

forward-only cursor

See nonscrollable cursor.

fractional second

The portion of a second that is greater than 0 but less than 1.

fragmentation

The separation of the index into pieces as a result of inserts and deletions in the index.

free space

The total amount of unused space in a page, data set, file, or storage medium. Free space is the space that is not used to store records or control information.

free space control record (FSCR)

A record containing approximations of available space for each of the next 500 pages. In multidimensional clustering (MDC) or insert time clustering (ITC) tables, there is one FSCR for each block. The FSCR is stored on the first page of each block and covers only the pages in that block.

FSCR

See free space control record.

full access state

A state indicating that both read access and write access to a table are allowed.

full outer join

A join whose result consists of the matched rows of the two tables that were joined and the unmatched rows of both tables. See also join, left outer join, outer join, right outer join.

full refresh

In data replication, the process of loading a target table with data from a source table. See also change-capture replication.

fullselect

A subselect, a values-clause, or a number of both that are combined by set operators. Fullselect specifies a result table. If UNION is not used, the result of the fullselect is the result of the specified subselect. See also scalar fullselect.

fully escaped mapping

A mapping of characters in an SQL identifier to characters in an XML name where some characters might be represented using XML character escapes.

function

A relationship between a set of input data values and a set of result values that is used to extend and customize SQL or XQuery. Functions are invoked from elements of SQL statements such as the select list or the FROM clause and from XQuery as primary expressions. See also aggregate function, built-in function, external function, routine, row function, scalar function, sourced function, SQL function, table function, user-defined function.

function body

The implementation of the logic of a function. See also routine body.

function definer

The authorization ID that was used to process the CREATE FUNCTION statement.

function directory

A DB2 database directory that is used to store the executable files and libraries that are associated with users' external routines (procedures, functions, and methods).

function invocation

The use of a function together with any argument values being passed to the function body. The function is invoked by its name.

function mapping

In a federated system, a mapping between a data source function and an existing DB2 database function. The federated system supplies default mappings between existing built-in data source functions and built-in DB2 database functions; the default mappings are in the wrapper. The DB2 counterpart function can be either a complete function or a function template. See also function template.

function path

See SQL path.

function resolution

The process, internal to the database manager, by which a particular function instance is selected for invocation. The function name, the data types of the arguments, and the SQL path are used to make the selection.

function selection

See function resolution.

function shipping

The process of sending the subsections of a request to the specific database partition that contains the applicable data.

function signature

The logical concatenation of a fully qualified function name with the data types of all of its parameters.

function template

A DB2 database function that forces the federated server to call a data source function. See also function mapping.

fuzzy search

A search that can find words with spellings that are similar to that of the search term.

G

gap

In SQL replication, a range of log or journal records that the Capture program cannot read. The changed data in a gap can be lost.

gauge

An indicator for the current value for an item. See also counter.

GBP

See group buffer pool.

General Parallel File System (GPFS)

A high-performance shared-disk file system that can provide data access from nodes in a clustered system environment.

generated column

A column for which the database manager assigns the value. An example of a generated column is an identity column, row change timestamp column, or row-begin column. See also generated expression column, row-begin column, row-end column, transaction-start-ID column.

generated expression column

A generated column that is defined using an expression. See also generated column.

generic table function

A table UDF whose output table format is specified when the UDF is referenced, instead of when the UDF is defined.

geocoder

In DB2 Spatial Extender, a scalar function that translates existing data into data that can be understood in spatial terms. For example, a geocoder that is supplied by Spatial Extender translates United States addresses into instances of a spatial data type. Another geocoder might translate the identifier of a shelf in a warehouse into data that identifies the location of that shelf in the warehouse.

geodesic distance

The shortest path between two points on the ellipsoidal shape of the Earth.

geographic coordinate system

In DB2 Spatial Extender, a reference system that uses latitude and longitude to define locations on the surface of a sphere or spheroid.

geographic feature

An object on the surface of the Earth (such as a city or river), a space (such as a safety zone around a hazardous site), or an event that occurs at a location (such as an auto accident that occurred at a particular intersection).

getpage

An operation in which DB2 for z/OS accesses a data page.

GLM

See global lock manager.

global catalog

In a federated system, the database system catalog. The catalog contains information about objects in the federated database and at the data source. The catalog also contains information about the entire federated system. The information in the global catalog is used by the query optimizer to plan the best way to process SQL statements.

global database configuration parameter

A database configuration parameter that has a single value across all members for a database in a DB2 pureScale environment.

global lock manager (GLM)

A component that runs on a cluster caching facility and coordinates the lock requests made by the local lock manager running on each member. See also local lock manager.

global optimization guideline

An optimization guideline that applies to all DML statements for which an optimization profile is in effect. See also optimization guideline.

global optimizer

In a federated system, a feature of the DB2 SQL Compiler that analyzes distributed queries and determines the most efficient way to run them. The global optimizer evaluates queries based on resource cost.

global record

In SQL replication, the row in the register table that defines global replication characteristics for an instance of the Capture program.

global registry

A file created during a root installation of a DB2 product on a UNIX or Linux system. The file contains information such as service records, instance records (instance name, instance path), variable records (variable names, variable values), and DAS information.

global sequence

An XML sequence that contains node references that are potentially on different database partitions.

global transaction

A unit of work in a distributed transaction processing environment in which multiple resource managers are required.

global variable

A representation of a value that can be accessed and sometimes modified by SQL statements that are running within the same scope. This scope can be either a session or a database, depending on how the global variable is defined. See also built-in global variable, database global variable, session global variable, special register, user-defined global variable, variable.

GPFS

See General Parallel File System.

grant

To give a privilege or authority to an authorization identifier.

graphic character

A DBCS character.

graphic data

Data that has an associated coding representation that defines how to interpret each specific pattern of bits that are grouped into one or more 2-byte sequences.

graphic string

A sequence of double-byte character set (DBCS) characters.

gross lock

The shared, update, or exclusive mode locks on a table, partition, or table space. See also exclusive lock, shared lock.

group

In a satellite environment, a collection of satellites that share characteristics such as the database configuration and the application that runs on the satellites.
A logical organization of users whose membership allows them to perform the same activities or provide the same authority to access resources.

group buffer pool (GBP)

A DB2 for z/OS coupling facility cache structure that is used by a data sharing group to cache data and to ensure that the data is consistent for all members.
A group cache structure that is used by a DB2 pureScale environment to cache data and to ensure that all members read the most recently committed version of a page. See also local buffer pool.

group buffer pool duplexing

The ability to write data to two instances of a group buffer pool structure: a primary group buffer pool and a secondary group buffer pool.

group crash recovery

The portion of the group restart process where a specific database is brought back to a transactionally consistent state after a failure in a DB2 pureScale instance. Either the primary and secondary cluster caching facilities both failed, or the primary cluster caching facility failed when the secondary cluster caching facility was not in peer state. See also member crash recovery.

group name

The z/OS XCF identifier for a data sharing group.

group restart

The act of restarting a complete DB2 pureScale instance (cluster caching facilities and members) and performing group crash recovery on each database. See also member restart.

group scope

In a DB2 pureScale environment, the scope of a command that affects all members of a data sharing group.

guest member

A member that is started on an active host other than its home host for the purpose of restart light. See also member, resident member, restart light.

H

HADR

See high availability disaster recovery.

HADR log spooling

The ability for the log replay process on the HADR standby database to read transaction logs from disk and the log receive buffer, instead of from only the log receive buffer. This ability prevents transactions on the primary database from being blocked when replay on the standby database is relatively slow during a primary database load spike.

handle

A variable that represents an internal structure within a software system.
A character string that is created by an extender that is used to represent an image, an audio, or a video object in a table. A handle is stored for an object in a user table and in administrative support tables. In this way, an extender can link the handle that is stored in a user table with information about the object that is stored in the administrative support tables.

handshake

The exchange of messages at the start of a Secure Sockets Layer session that allows the client to authenticate the server using public key techniques (and, optionally, for the server to authenticate the client) and then allows the client and server to cooperate in creating symmetric keys for encryption, decryption, and detection of tampering.

hang

To become unresponsive to user commands and to stop or seem to stop processing.

hard CPU shares

An attribute that defines the relative share of CPU resources on a host or LPAR that the WLM dispatcher allows a particular service class to use but not exceed, even if additional CPU resources are available.

hash partitioning

A data distribution strategy in which a hashing algorithm is applied to a distribution key value to determine the database partition to which a row is assigned.

health

The general condition or state of the database environment.

health indicator

A measure of some aspect of the health of an object. Threshold-based health indicators identify whether the behavior of an object is within ranges of normal, warning, and alarm. State-based health indicators identify whether the state of an object is normal or non-normal. See also health monitor alert.

health monitor

An instance-level monitor that creates alerts based on a health indicator exceeding a threshold or being in non-normal state. The monitor sends notifications to the notification log and also sends emails and pages to contacts on its notification list.

health monitor alert

An alert that is generated by the health monitor and is based on the type of health indicator. See also health indicator.

health notification contact list

A set of contacts that receives notifications when health alerts occur.

health snapshot

Health data, retrieved from the database manager at a point in time, for a set of database objects.

heap

A logical grouping of memory that fulfills the needs of a particular component. For example, the utility heap memory is used by DB2 utilities such as backup, restore, and load.

heuristic decision

A decision made by a user to commit or roll back a transaction on a DB2 database.

hierarchy

A defined relationship among a set of attributes that are grouped by levels in the dimension of a cube model.

high availability disaster recovery (HADR)

A disaster recovery solution that uses log shipping and provides data to a standby system if a partial or complete site failure occurs on a primary system. See also asynchronous mode, log shipping, Q replication, standard database, standby database, super asynchronous mode.

hiperspace

A high-performance, virtual-storage space of up to 2 gigabytes (GB). Unlike an address space, a hiperspace contains only user data and does not contain system control blocks or common areas; code does not execute in a hiperspace. Unlike a data space, data in a hiperspace cannot be referenced directly; data must be moved to an address space in blocks of 4 KB before being processed.

historical row

A row in a history table. See also history table.

history table

A table that is used by the database manager to store historical versions of rows from the associated system-period temporal table. See also historical row, system-period temporal table.

holdable result set

A result set that is associated with a cursor that was created with the WITH HOLD clause.

hole

A row of a result table that cannot be accessed because a delete operation or an update operation has been performed on that row. See also delete hole, update hole.

home host

The host on which a member is created and on which that member typically runs.

host

In TCP/IP, any system that has at least one IP address associated with it.

host identifier

A name that is declared in the host program.

host language

Any programming language in which SQL statements or XQuery expressions can be embedded.

host program

An application program that is written in a host language and that contains embedded SQL statements or XQuery expressions.

host structure

In an application program, a structure that contains a list of host variables that can be referred to by embedded SQL statements.

host variable

In an application program, a programming variable that is referred to by embedded SQL statements. The value of the host variable comes from the host program when a statement is executed or a cursor is opened. A host variable is a colon followed by a name (:name). See also parameter marker.

host variable array

An array of elements, each of which corresponds to a value for a column. The dimension of the array determines the maximum number of rows for which the array can be used.

HTML

See Hypertext Markup Language.

Hypertext Markup Language (HTML)

A markup language that conforms to the Standard Generalized Markup Language (SGML) standard and was designed primarily to support the online display of textual and graphical information, including hypertext links.

I

IBM data server client (data server client)

A client that determines the location of a remote database, manages the transmission of requests to the database server, and returns the results.

IBM Data Server Client (Data Server Client)

An application development product that allows applications to be developed on a client workstation to access remote database servers, including DB2 family databases, through the DB2 Connect products.

IBM data server driver copy (data server driver copy)

A single instance of an installation of IBM Data Server Driver Package.

IBM Data Server Provider for .NET (Data Server Provider for .NET)

An extension of the ADO.NET interface that allows .NET applications to access a DB2 or Informix Dynamic Server (IDS) database through a secure connection, run commands, and retrieve results.

IBM Support Assistant (ISA, Support Assistant)

A software serviceability workbench that helps to reduce support costs and improve customer satisfaction by increasing the customers' ability to resolve software challenges on their own.

identity column

A generated column that is defined with the AS IDENTITY clause. An identity column provides a way for the database manager to automatically generate a numeric value for each row that is inserted into a table. A table can have no more than one identity column.

idle agent

A database agent that currently does not have a database connection or an application association. See also active agent.

ignorable white space

Any white space characters in an XQuery expression that are not significant to the expression results.

IIH

See installation-initiating host.

image copy

An exact reproduction of all or part of a table space. DB2 for z/OS provides utility programs to make full image copies (to copy the entire table space) or incremental image copies (to copy only those pages that were modified since the last image copy).

immediate index cleanup rollout

A rollout in which index cleanup is performed synchronously with the deletion of the portion of the MDC table. See also rollout.

implicit casting

The automatic conversion of data of one data type to data of another data type based on an implied set of conversion rules. This automatic conversion occurs in support of weak typing. See also strong typing, weak typing.

implicit privilege

A privilege that accompanies the ownership of an object, such as the privilege to drop that object. Different authority levels and database authorities can also provide implicit privileges on one or more objects. See also explicit privilege.
A privilege on one or more data objects that are referenced by a package. During package execution, the user ID running the package inherits within certain boundaries the privileges of the user ID that bound the package. See also authority level.

implicit rebind

In DB2 for Linux, UNIX, and Windows, a process by which packages that are invalid are rebound automatically when an application process begins to use that package. See also rebind.

implicit time zone

In DB2 XQuery, Coordinated Universal Time (UTC), which is used when a date, time, or time zone value that does not have a time zone is used in a comparison or arithmetic operation.

implicit trusted connection

A trusted connection that allows the acquisition of only a trusted context default role. See also trusted connection.

import

To copy data from an external file, using formats such as PC/IXF, DEL, or ASC, into database tables. See also export.

IMS

See Information Management System.

IMS attachment facility

A DB2 for z/OS subcomponent that uses z/OS subsystem interface (SSI) protocols and cross-memory linkage to process requests from IMS to DB2 for z/OS and to coordinate resource commitment.

IMS Database Manager (IMS DB)

A database system that processes concurrent database calls and offers high performance for a variety of applications, ranging from those with moderate volumes to extremely high volumes and those with simple data structures to complex data structures.

IMS DataPropagator

A product that enables data to be replicated between IMS and DB2 databases.

IMS DB

See IMS Database Manager.

IMS TM

See IMS Transaction Manager.

IMS Transaction Manager (IMS TM)

A data communication system that provides high-volume, high-performance, high-capacity, low-cost transaction processing for both IMS DB and DB2 databases.

in-abort

A status of a unit of recovery that occurs when DB2 for z/OS fails after a unit of recovery begins to be rolled back but before the process is completed. DB2 for z/OS continues to back out the changes when the process restarts.

incremental backup

A copy of all database data that has changed since the most recent successful full backup operation. An incremental backup is also known as a cumulative backup image because each incremental backup includes the contents of the previous incremental backup.

incremental bind

In DB2 for Linux, UNIX, and Windows, a process by which SQL statements are bound during the execution of an application process, because they could not be bound during the bind process, and VALIDATE(RUN) was specified. See also incremental bind statement.

incremental bind statement

In DB2 for Linux, UNIX, and Windows, SQL statements that are neither fully static nor fully dynamic. Like static statements, they are embedded within an application, but like dynamic statements, they are prepared during the execution of an application. See also deferred embedded SQL, dynamic SQL, incremental bind, static SQL.

independent

Pertaining to an object (row, table, or table space) that is neither a parent nor a dependent of another object.

index

A set of pointers that is logically ordered by the values of a key. Indexes provide quick access to data and can enforce uniqueness of the key values for the rows in the table.

index-controlled partitioning

A type of partitioning in which partition boundaries for a partitioned table are controlled by values that are specified on the CREATE INDEX statement. Partition limits are saved in the LIMITKEY column of the SYSIBM.SYSINDEXPART catalog table.

index data consistency

A condition in which all of the data rows in a database are valid data rows, all of the data rows are referenced in the index, there are no index keys referencing nonexistent data rows, and the column values in each index key match the corresponding column values in the referenced data rows. If the database does not maintain index data consistency, the database is corrupted.

index key

The set of columns in a table that is used to determine the order of index entries.

index manager

The component of the database manager that controls creating, removing, maintaining, and accessing the indexes defined in a database.

index matching

A task that the query complier performs to determine whether the query compiler can use an index to evaluate an SQL, SQL/XML, or XQUERY query. To use an index over XML data, the data types specified in the query search condition must match indexed data types, and the query return set must be more restrictive than the set of the nodes that are indexed.

index over XML data

In DB2 databases, an index that provides efficient access to nodes within an XML document by providing index keys that are based on XML patterns.

index partition

An index on a data partition of a partitioned table. See also partitioned index.

index scan

The accessing of an index by the database manager to narrow the set of qualifying rows before accessing a base table, to order output, or to retrieve requested column data directly when all of the requested data is in the index.

index space

A page set that is used to store the entries of one index.

index specification

In a federated system, a set of metadata about a data source object index that the query optimizer uses to expedite the processing of distributed requests. When a nickname is created for a data source object, the federated server gathers index information about that object and stores the information in the global catalog.

indicator column

A 4-byte value that is stored in a base table in place of an LOB column.

indicator variable

A variable that is used with a host variable to represent the SQL null value in an application program. See also extended indicator variable.

individual privilege

A privilege that is granted on a single data object.

indoubt

The status of a unit of recovery that occurs when the database manager fails after it finishes its phase 1 commit processing and before it starts phase 2. At emergency restart, the status of the unit of recovery is indoubt until the commit coordinator indicates to the database manager whether the unit of recovery is to be committed or rolled back.

indoubt resolution

The process of resolving the status of an indoubt logical unit of work to either the committed or the rollback state.

indoubt transaction

A transaction in which one phase of a two-phase commit completes successfully but the system fails before a subsequent phase can complete.

infinity

In decimal floating-point operations, a signed value that is mathematically greater in magnitude than any other decimal floating-point number. See also decimal floating-point number.

informational constraint

A rule used by the SQL compiler to improve query performance without requiring additional data verification. See also constraint.

informational message

In Q replication and event publishing, a message about the status of the Q Capture program, a Q subscription, or a publication.

Information Management System (IMS)

Any of several system environments that have a database manager and transaction processing that can manage complex databases and terminal networks.

initialization fullselect

The first fullselect in a recursive common table expression that gets the direct children of the initial value from the source table.

inline SQL PL

A subset of SQL procedural language that can be used in SQL functions, triggers, and dynamic compound statements. See also compiled SQL PL.

inner join

The result of a join operation that includes only the matched rows of both tables that are being joined. See also join, outer join.

inoperative package

A package that is not usable because one or more user-defined functions, procedures, or methods on which the package depends were dropped.

inoperative trigger

A trigger that is not usable because an object on which the trigger depends was dropped or made inoperative or a privilege on which the trigger depends was revoked.

inoperative view

A view that is not usable because a privilege on an underlying table was revoked; a table, an alias, or a function was dropped; a superview was made inoperative; or another view on which the view depends was dropped or was made inoperative.

in-scope namespace

In XQuery, a property of an element node that defines a set of namespace bindings that associate namespace prefixes with URIs and defines the set of namespace prefixes that is available for interpreting QNames within the scope of the element. See also qualified name.

in-scope schema type

The built-in data types that are specified in the World Wide Web Consortium XML Schema recommendation or the predefined data types in the namespace http://www.w3.org/2005/xpath-datatypes.

insensitive cursor

A cursor that is not sensitive to inserts, updates, or deletes that are made to the underlying rows of a result table after the result table has been materialized. See also cursor, cursor sensitivity.

insert rule

A condition enforced by the database manager that must be met before a row can be inserted into a table.

insert time clustering table (ITC table)

A table that clusters data according to the time at which it is inserted into the table. An ITC table is similar to a multidimensional clustering table, but an ITC table has no user-specified dimensions; instead, the rows are clustered in a single cell.

insert trigger

A trigger that is activated by an insert operation on the table or view that is specified in the trigger definition. See also delete trigger, instead of trigger, trigger, update trigger.

installation

A set of artifacts from one or more DB2 database products.

installation-initiating host (IIH)

A host from which a user installs and configures a DB2 pureScale instance.

installation program

A program that prepares a software package to run on the computer. During installation, a component of the setup program is commonly copied to and left on the hard drive so that the user can customize the default settings of the program.

instance

An entity to which a set of operations can be applied and that has a state that stores the effects of the operations.

instance-owning database partition

In partitioned database environments, the database partition that has the superset of features and products within the cluster. The instance-owning database partition is identified by the host name in the first line of the db2nodes.cfg file and has the smallest database partition number (normally, 0).

instantiable structured type

A structured type that can be used for creating database objects. A structured type that is not instantiable cannot be used for creating database objects; however, such a type can be used to define subtypes which, in turn, can be instantiable.

instead of trigger

A trigger that is associated with a single view and is activated by an insert, update, or delete operation on the view and that defines how to propagate the insert, update, or delete operation on the view to the underlying tables of the view. See also after trigger, before trigger, delete trigger, insert trigger, trigger, update trigger.

integrated text search server

The Enterprise Content Management text search server that is installed by using the DB2 installation program.

integrity processing

The process of populating identity and generated columns, refreshing materialized query tables, propagating updates to staging tables, and performing constraints checking. See also set integrity pending.

interactive SQL

A set of SQL statements that is provided through an interface such as the Command Center or command line processor. These statements are processed as dynamic SQL statements. For example, an interactive SELECT statement can be processed dynamically using the DECLARE CURSOR, PREPARE, DESCRIBE, OPEN, FETCH, and CLOSE statements.

Interactive System Productivity Facility/Program Development Facility (ISPF/PDF)

An IBM licensed program that provides a work environment for the development of programs and the use of functions like Edit and Browse.

interleave fetch

The action of fetching part of a result set from one cursor, fetching part of a different result set from at least one other cursor, and fetching again from the original cursor. Fetches can continue from the open cursors in random order.

internal CCD table

A CCD table that is not a registered replication source and therefore cannot be subscribed to. An internal CCD table is identified by the CCD_OWNER and CCD_TABLE columns for the row of the associated registered replication source. See also consistent-change-data table, external CCD table.

Internet Protocol (IP)

A protocol that routes data through a network or interconnected networks. This protocol acts as an intermediary between the higher protocol layers and the physical network.

interpartition parallelism

A single database operation (for example, index creation) that is run in parallel across the partitions of a partitioned database. See also intrapartition parallelism, intraquery parallelism, massively parallel processing.

interprocess communication (IPC)

A mechanism of an operating system that allows processes to communicate with each other within the same computer or over a network.

interval timing

In SQL replication, the process of controlling how frequently a replication subscription cycle runs.

intrapartition parallelism

The subdivision of a single database operation (for example, index creation) into multiple parts, which are then executed in parallel within a single database partition. See also interpartition parallelism.

intraquery parallelism

The ability to process parts of a single query at the same time using intrapartition parallelism, interpartition parallelism, or both. See also interpartition parallelism.

invalid object

An object that was created but is not yet fully functional or is no longer fully functional. An object can become invalid if it depends on another object that was dropped or modified by a DDL statement or if it depends on a privilege that was revoked. See also object.

invariant character set

A set of characters, such as the syntactic character set, having the same code point assignments in all coded character sets or code pages using a given encoding scheme. See also code page, coded character set, encoding scheme.

IP

See Internet Protocol.

IP address

A unique address for a device or logical unit on a network that uses the Internet Protocol standard. See also dynamic IP address, static IP address.

IPC

See interprocess communication.

ISA

See IBM Support Assistant.

isolation level

An attribute that defines the degree to which an application process is isolated from other concurrently executing application processes. Isolation levels generally relate to the behavior of an application with respect to locks. See also cursor stability, read stability, repeatable read, uncommitted read.

ISPF/PDF

See Interactive System Productivity Facility/Program Development Facility.

ITC table

See insert time clustering table.

item

In XQuery, a part of a sequence that is either an atomic value or a node. See also atomic value, node.

J

Java archive: A compressed file format for storing all of the resources that are required to install and run a Java program in a single file.
Java Database Connectivity (JDBC): An industry standard for database-independent connectivity between the Java platform and a wide range of databases. The JDBC interface provides a call level interface for SQL-based and XQuery-based database access. See also Open Database Connectivity.
Java Development Kit (JDK): See Java SE Development Kit.
Java SE Development Kit: The name of the software development kit that Sun Microsystems provides for the Java platform.
JDBC: See Java Database Connectivity.
JDBC driver: A program included with database management systems to support the JDBC standard for providing access from Java applications to relational databases.
JDK: See Java Development Kit.
JFS: See journaled file system.
job scheduler: A program used to automate certain tasks for running and managing database jobs.
join: An SQL relational operation in which data can be retrieved from two tables, typically based on a join condition specifying join columns. See also equijoin, full outer join, inner join, left outer join, outer join, right outer join, star join.
joined table: An intermediate result table that is the result of either an inner join or an outer join.
journaled file system (JFS): The local file system in the AIX operating system.

K

Kerberos: A network authentication protocol that is based on symmetric key cryptography. Kerberos assigns a unique key, called a ticket, to each user who logs on to the network. The ticket is embedded in messages that are sent over the network. The receiver of a message uses the ticket to authenticate the sender.
Kerberos ticket: A transparent application mechanism that transmits the identity of an initiating principal to its target. A simple ticket contains the identity of the principal, a session key, a timestamp, and other information, which are sealed using the secret key of the target.
key: A column or an ordered collection of columns that is identified in the description of a table, index, or referential constraint. The same column can be part of more than one key.
key database: In security, a storage object, either a file or a hardware cryptographic card, where identities and private keys are stored for authentication and encryption purposes. Some key databases also contain public keys. See also stash file.
key file: In computer security, a file that contains public keys, private keys, trusted roots, and certificates. See also stash file.
key ring: See key file.
key-sequenced data set (KSDS): A VSAM file or data set whose records are loaded in key sequence and controlled by an index.
keystore: See key database.
keyword: One of the predefined words of a programming language, artificial language, application, or command. See also operand.
kind test: A form of a node test that can select nodes based on their kind and name. See also node test.
KSDS: See key-sequenced data set.

L

label-based access control (LBAC)

A security mechanism that uses security labels to restrict user access to individual table rows and columns. See also security label, security policy.

labeled duration

A number that represents a duration of years, months, days, hours, minutes, seconds, or microseconds.

large object (LOB)

A sequence of bytes with a size ranging from 0 bytes to 2 gigabytes less 1 byte. There are three types of LOBs: binary large objects (binary), character large objects (single-byte character or mixed), and double-byte character large objects (double-byte character).

large table space

A table space that stores persistent data in database-managed space but that has a larger space limit than that of a regular table space. See also permanent table space.

latch

An internal mechanism for controlling concurrent events or the use of system resources.

latency

In replication, part or all of the approximate difference between the time that a source table is changed and the time that the change is applied to the corresponding target table. See also Apply latency, Capture latency, end-to-end latency, Q Apply latency, Q Capture latency.

LBAC

See label-based access control.

LBAC credentials

In label-based access control, the set of security labels and exemptions held by a database user. See also exemption.

LBP

See local buffer pool.

LCID

See log control interval definition.

LDS

See linear data set.

leaf page

A page that contains pairs of keys and record identifiers and that points to actual data. See also nonleaf page.

left outer join

A join whose result consists of the matched rows of the two tables that were joined and the unmatched rows of the first table. See also full outer join, join, outer join, right outer join.

length attribute

A value associated with a string that represents the declared fixed length or maximum length of the string.

level

A set of one or more related attributes that work together as one logical step in a hierarchy. Attributes can function in one or more roles in a level.

lexical QName

An optional namespace prefix and a local name. If the namespace prefix is present, it is separated from the local name by a colon.

lifetime

The elapsed time from when a non-nested activity is identified by the database manager until the activity finishes running, as measured on the coordinator partition.

linear data set (LDS)

A VSAM data set that contains data but no control information. An LDS can be accessed as a byte-addressable string in virtual storage.

linkage editor

A computer program for creating load modules from one or more object modules or load modules by resolving cross-references among the modules and, if necessary, adjusting addresses.

link-edit

To create a loadable computer program by using a linkage editor.

list

A type of object, which DB2 utilities can process, that identifies multiple table spaces, multiple index spaces, or both. A list is defined with the LISTDEF utility control statement.

list prefetch

An access method that takes advantage of prefetching even in queries that do not access data sequentially. A list prefetch is done by scanning an index and collecting record identifiers before any data pages are accessed. These record identifiers are then sorted, and data is prefetched using this list.

little endian

A format for storage or transmission of binary data in which the least significant value is placed first. See also big endian.

LLM

See local lock manager.

load agent

The process that coordinates the loading of data to each database partition. See also partitioning agent, pre-partitioning agent.

load authority

An access level that gives LOAD utility privileges to load data into tables. See also authority level.

load copy

A backup image of data that was previously loaded and can be restored during rollforward recovery.

load module

A program in a form suitable for loading into main storage for execution.

load phase

In Q replication, the stage where a target table is loaded with data from a source table so that the two tables are synchronized. The load phase can be automatic or manual.

load utility

A nontransactional utility that performs block updates of table data.

LOB

See large object.

LOB locator

A mechanism that allows an application program to manipulate a large object (LOB) value in the database system. An LOB locator is a simple token value that represents a single LOB value. An application program retrieves an LOB locator into a host variable and can then apply SQL operations to the associated LOB value using the locator.

LOB table space

In DB2 for z/OS, a table space that contains all of the data for a particular LOB column in the related base table.

local

Pertaining to a device, file, or system that is accessed directly from a user system, without the use of a communication line.

local buffer pool (LBP)

A buffer pool that exists on a member and caches pages only for that member. See also group buffer pool.

local database

A database that is located on the workstation in use. See also remote database.

local database directory

A directory where a database is physically located. Databases that are displayed in the local database directory are located on the same node as the system database directory. See also system database directory.

locale

A setting that identifies language or geography and determines formatting conventions such as collation, case conversion, character classification, the language of messages, date and time representation, and numeric representation.

local lock manager (LLM)

A component that runs on each member and manages the lock requests made by the applications running on that member. See also global lock manager.

local non-root registry

A file created during a non-root installation of a DB2 product on a UNIX or Linux system. The file contains information such as service records (product level, installation path), instance records (instance name, instance path), and variable records (variable names, variable values).

local update

An update to a base table, not to its replica.

location name

The unique name of a database server. An application uses the location name to access a DB2 database server.

location path

An XPath expression that selects a set of nodes based on the evaluation of a series of navigation steps and filters, starting from the current context node. Navigation steps are separated by the / character. Steps can be expressed using a sequence of XML tags or abbreviations defined by XPath.

locator variable

A host variable that contains the locator representing a LOB value on the application server.

lock

A means of preventing uncommitted changes made by one application process from being perceived by another application process and for preventing one application process from updating data that is being accessed by another process. A lock ensures the integrity of data by preventing concurrent users from accessing inconsistent data.
A means of serializing a sequence of events or serializing access to data.

lock escalation

The response that occurs when the number of locks issued for one agent exceeds the limit specified in the database configuration; the limit is defined by the maxlocks configuration parameter. During a lock escalation, locks are freed by converting multiple locks on rows of a table into one lock on a table. This process is repeated until the limit is no longer exceeded.

lock mode

A representation for the type of access that concurrently running programs can have to a resource that a lock is holding.

lock object

The resource that is controlled by a lock.

lock size

The amount of data that is controlled by a lock on table data. Examples of lock size values are table, row, and page.

log

A collection of records that sequentially describes the events that occur in a system.
A record of events.

log control interval definition (LCID)

A suffix of the physical log record that tells how record segments are placed in the physical control interval.

log file

The file where the log of events is recorded.

log head

The oldest written log record in the active log.

logical agent

An agent that represents the client or application connection.

logical claim

A claim on a logical partition of a nonpartitioning index. See also claim.

logical data group

A collection of data elements that gathers database system monitoring information for a specific scope of database activity. The snapshot monitor and event monitor each has its own sets of logical data groups. See also monitor element.

logical drain

A drain on a logical partition of a nonpartitioning index. See also drain.

logical index

A component of a user-defined index over XML data that contains XML pattern information specified by the CREATE INDEX statement. See also physical index.

logically detached partition

A partition that was successfully processed by the ALTER TABLE statement with the DETACH PARTITION clause, but is not yet a stand-alone table. The partition is still accessible to some queries that began reading the partition before the statement was issued. See also asynchronous partition detach.

logical operator

A symbol, such as AND, OR, or NOT, that represents an operation on logical expressions.

logical partition (LP, LPAR)

In a partitioned database environment, a database partition server on a processor that has more than one database partition server assigned to it.
A set of key or RID pairs in a nonpartitioning index that is associated with a particular partition.

logical recovery pending (LRECP)

The state in which data and the index keys that refer to that data are inconsistent.

logical server

In replication, on Linux, UNIX, and Windows, a DB2 database.
On z/OS, a subsystem that is running DB2 for z/OS.

logical table

In Q replication, all of the copies of one table that are distributed across servers in bidirectional or peer-to-peer replication. If a user replicates two logical tables, then copies of both tables are distributed across the servers.

logical unit of work (LUW)

The processing that a program performs between synchronization points.

log merge

See log stream merge.

log record

A discrete piece of information that describes an event that occurs in a system. For example, a record of an update to a database performed during a unit of work (UOW) is written after the log tail of the active log.

log record header (LRH)

A prefix, in every log record, that contains control information.

log record sequence number (LRSN)

A unique identifier for a log record that is associated with a data sharing member. DB2 for z/OS uses the LRSN for recovery in the data sharing environment. See also log sequence number.

log sequence number (LSN)

In DB2 for Linux, UNIX, and Windows, an ordered identifier for a log record. The log sequence number is used by recovery operations. See also log record sequence number.

log shipping

The process of copying whole log files to a standby machine, either from an archive device or through a user exit program running against the primary database. See also high availability disaster recovery.

log stream

A set of log files that is associated with a member or the result of merging the logs of multiple members. See also log stream merge.

log stream merge

The process of ordering log records from the log streams of multiple members so that the merged log stream is in chronological order. See also log stream.

log table

A table created by DB2 Net Search Extender or DB2 Text Search that contains information about text documents to be indexed.

log tail

The log record that was written most recently in an active log.

long table space

See large table space.

LP

See logical partition.

LPAR

See logical partition.

LRECP

See logical recovery pending.

LRH

See log record header.

LRSN

See log record sequence number.

LSN

See log sequence number.

LUW

See logical unit of work.

M

maintenance window

A user-defined time period for running only required automatic maintenance activities. See also automatic maintenance.

manual load

In Q replication, a load process in which the user loads data into a target table and then notifies the replication program. See also automatic load.

market basket analysis

A data mining process for analyzing sales transaction data that determines which products customers purchase together. Retail organizations can use market basket analysis to optimize the placement of products on websites or on shelves.

masking character

A character used to represent optional characters at the front, middle, or end of a search term. Masking characters are normally used for finding variations of a term in a precise index.

mass delete

The deletion of all rows of a table.

massively parallel processing (MPP)

The coordinated execution of a single request by multiple single-processor computers in a shared-nothing environment (in which each computer has its own memory and disks). See also database partitioning, interpartition parallelism.

master table

In SQL replication, specifically in update-anywhere replication, the original source table for data in the replica table. If replication conflict detection is enabled, changes made to the master table are retained, whereas changes made to the replica table are rejected. See also conflict detection, replica table, update-anywhere replication.

materialize

To place an LOB value into contiguous storage. Because LOB values can be very large, DB2 for z/OS avoids materializing LOB data until doing so becomes absolutely necessary.
To put rows from a view or nested table expression into a work file for additional processing by a query.

materialized query table (MQT)

A base table whose definition is based on the result of a query and whose data is in the form of precomputed results that are taken from the table or tables on which the MQT definition is based. See also summary table.

MBCS

See multibyte character set.

MDC table

See multidimensional clustering table.

measure

Metrics such as count, maximum, minimum, sum, or average that are used in a fact table. Measures can be calculated with an SQL expression or mapped directly to a numeric value in a column.

member

A single database manager process that runs DB2 server software on a physical or logical host. See also guest member, resident member.
In multidimensional clustering, the element of a dimension. See also dimension.

member crash recovery

In a DB2 pureScale instance, the process of recovering the database transactions after a member failure. Recovery is done using the log stream of a single member and ensures consistency of the transactions in the log stream. See also group crash recovery.

member name

The z/OS XCF identifier for a particular DB2 for z/OS subsystem in a data sharing group.

member restart

The act of restarting a member after a member failure and performing member crash recovery on each database in the DB2 pureScale instance. See also group restart.

memory set

A group of one or more memory allocations from the operating system that are managed by the database manager. Memory in a specific memory set shares common attributes, such as the general purpose for which the memory is used, the expected volatility of the memory, and any constraints on its growth.

menu

A displayed list of items from which a user can make a selection.

metadata

Data that describes the characteristics of data; descriptive data.

method

A database object that encapsulates procedural logic to provide behavior for a structured type. A method can be implemented as an SQL method or an external method. See also external method, routine, SQL method.

method body

The implementation of the logic of a method. See also routine body.

migrate

To move data from one location to another.

mining model

The output of a data mining function that describes patterns and relationships that are discovered in historical data. A data mining model can be applied to new data for predicting likely new outcomes.

mixed character string

A string containing a mixture of single-byte and multibyte characters.

module

A database object that is a collection of other database objects, including conditions, data types, functions, procedures, and variables. See also module body, module object, package, routine prototype.

module body

For a given module, the unpublished module objects and the routine bodies of published module routines. See also module.

module initialization procedure

A procedure that is automatically called when any module routine or variable is first referenced in a session.

module object

A database object defined in a module. See also condition, module, published module object.

Monitor control server

In replication, a database that contains the Monitor control tables, which store information about alert conditions that the Replication Alert Monitor monitors. See also control server.

monitor element

A data structure that is used by the system monitor to store information about a particular aspect of the database system status. Monitor elements collect data for one or more logical data groups. Each monitor element collects one of the following specific types of data: counter, gauge, watermark, textual information, or timestamp. See also logical data group.

monitor qualifier

A case-sensitive character string that identifies an instance of a Replication Alert Monitor process.

monitor switch

A database manager parameter that is manipulated by the user to control the type and quantity of information that is returned in performance snapshots.

monotonic

Pertaining to an expression or function whose set of all possible results preserves the order of the set of inputs. An expression or function that is used to derive a generated column and that is monotonically decreasing, increasing, nondecreasing, or nonincreasing can increase functionality on tables organized by dimensions.

mount point

In Linux operating systems and in UNIX operating systems such as the AIX operating system, the directory at which a file system is mounted and under which other file systems can be mounted.

MPP

See massively parallel processing.

MQT

See materialized query table.

multibyte character set (MBCS)

A character set that represents single characters with more than a single byte. See also double-byte character set, single-byte character set, Unicode.

multidimensional

In the DB2 OLAP Server, pertaining to a method of referencing data through three or more dimensions. An individual data value in a fact table is the intersection of one member from each dimension.

multidimensional analysis

The process of assessing and evaluating an enterprise on more than one level.

multidimensional clustering table (MDC table)

A table whose data is physically organized into blocks along one or more dimensions, or clustering keys, specified in the ORGANIZE BY DIMENSIONS clause.

multidirectional replication

In Q replication, a replication configuration that includes peer-to-peer or bidirectional replication.

multiple logical partitions

A partitioned database environment with multiple database partition servers installed on one computer.

Multiple Virtual Storage (MVS)

An IBM operating system that accesses multiple address spaces in virtual storage. See also Base Control Program.

multisite update

Distributed relational database processing in which data is updated in more than one location within a single unit of work. See also unit of work.

multitasking

A mode of operation in which two or more tasks can be performed at the same time.

multi-tier replication

In replication, a replication configuration in which changes are replicated from a replication source in one database to a replication target in another database, and changes from this replication target are replicated again to a replication target in another database. See also peer-to-peer replication, update-anywhere replication.

MVS

See Multiple Virtual Storage.

N

namespace

In XML and XQuery, a uniform resource identifier (URI) that provides a unique name to associate with the element, attribute, and type definitions in an XML schema or with the names of elements, attributes, types, functions, and errors in XQuery expressions.

namespace prefix

The portion of a qualified name that is mapped to a URI reference and serves as a proxy for a URI reference in a qualified name.

name test

A node test that consists only of a QName or a wildcard. See also node test.

NaN

See not-a-number.

NCName

See non-colonized name.

near synchronous mode

In high availability disaster recovery, the synchronization mode in which the primary database considers a transaction committed when it receives a message from the standby database confirming that the log data was received and written to the main memory of the standby system. See also peer state, synchronization mode.

negotiable lock

A lock whose mode can be downgraded, by agreement among contending users, to be compatible to all. A physical lock is an example of a negotiable lock.

nested savepoint

A savepoint that is included or positioned within another savepoint. Nested savepoints allow an application to have multiple levels of savepoints active at a time and allow the application to roll back to any active savepoint as required.

nested table expression

A fullselect surrounded by parentheses in a FROM clause.

nested type

A complex data type that references another complex data type. A nested type can be an array type with elements that are row or array types or can be a row type with fields that are row or array types.

network-mounted client

An IBM data server client whose code and configuration files are stored on a network path.

New Technology File System (NTFS)

One of the native file systems in Windows operating environments.

nickname

In a federated system, an identifier that is used in a distributed request to refer to a data source object. See also data source object.

no access state

A state indicating that neither read access nor write access to a table is allowed.

no data movement state

A state indicating that data movement operations within a table are not allowed.

node

In communications, an end point of a communication link or a junction common to two or more links in a network. Nodes can be processors, communication controllers, cluster controllers, terminals, or workstations. Nodes can vary in routing and other functional capabilities.
An instance of one of the node kinds that are defined by the XQuery and XPath data model. See also item, node kind, XQuery and XPath data model.
See database partition.

node directory

A directory that contains information that is necessary to establish communications from a client workstation to all applicable database servers.

node ID

See node identifier.

node identifier (node ID)

In a tree-like representation of XML instance documents, a unique pointer to a specific node. A node ID can also point to a node that is generated by a constructor.

node kind

A designation that defines a node according to the data that the node contains. The XQuery and XPath data model defines the following node kinds: document, element, attribute, text, processing instruction, and comment. See also node, processing instruction.

node test

A test that determines whether a condition is true for each node that is selected by a step in a path expression. See also kind test, name test, path expression, step.

non-colonized name (NCName)

A name that does not contain a colon character. A lexical QName consists of two NCNames, the namespace prefix and the local name, which are separated by a colon.

noncomplete CCD table

In SQL replication, a CCD table that is initially empty and has rows appended to it as changes are made to the replication source. See also complete CCD table.

noncondensed CCD table

In SQL replication, a CCD table that can contain more than one row for each key value. These duplicate rows represent the history of changes for the values in the rows of a table. See also condensed CCD table, consistent-change-data table.

noncumulative backup

See delta backup.

nondelimited ASCII format

A file format that is used to import data. A nondelimited ASCII file is a sequential ASCII file with row delimiters used for data exchange with any ASCII product; column values are not separated by delimiters.

non-deterministic function

A user-defined function whose result is not solely dependent on the values of the input arguments. That is, successive invocation with the same argument value can produce a different answer.

nonleaf page

An index page that contains keys and page numbers of other pages in the index (either leaf or nonleaf pages). Nonleaf pages never point to actual data. See also leaf page.

nonpartitioned index

An object that contains the index entries for all data partitions of a partitioned table. See also partitioned index.

nonpartitioned table

A table that does not use data partitions. See also partitioned table.

non-root installation

An installation performed by a non-root user.

non-root instance

A DB2 instance created by a non-root user from the DB2 product installed by that user.

non-root user

In Linux and UNIX operating systems, a user without root privileges.

nonscrollable cursor

A cursor that can be moved only in a forward direction. Nonscrollable cursors are sometimes called forward-only cursors or serial cursors. See also scrollable cursor.

normalization

The process of restructuring a data model by reducing its relations to their simplest forms. It is a key step in the task of building a logical relational database design. Normalization helps avoid redundancies and inconsistencies in data. An entity is normalized if it meets a set of constraints for a particular normal form (first normal form, second normal form, and so on). See also denormalization.

normal number

In floating-point representation, any nonzero number that has a nonzero digit as the leftmost digit of the significand. See also decimal floating-point number, subnormal number.

not-a-number (NaN)

In binary floating-point and decimal floating-point concepts, a value, not interpreted as a mathematical value, that contains a mask and a sequence of digits. See also decimal floating-point number.

not deterministic function

See non-deterministic function.

not fenced

Pertaining to a type, or characteristic, of a procedure or user-defined function that is defined to run in the database manager process. When this type of object is run (using the not fenced clause), the database manager is not protected from changes made by this object. See also fenced.

NTFS

See New Technology File System.

NULL

In the C language, a single character that denotes the end of a string.
In SQL, the value denoting the absence of data for a particular row and column.

nullable

The condition in which a value for a column, function parameter, or result can be absent.

null terminator

In C, the value that indicates the end of a string. For EBCDIC, ASCII, and Unicode UTF-8 strings, the null terminator is a single-byte value (X'00'). For Unicode UTF-16 and UCS-2 (wide) strings, the null terminator is a double-byte value (X'0000').

null value

A parameter position for which no value is specified.

numeric character reference

See character entity reference.

O

obfuscation

A process that encodes a portion of DDL statements that define database objects such as routines, triggers, views, or PL/SQL packages so that the embedded intellectual property cannot be read by users but is still understood by the database manager.

object

Anything that can be created or manipulated by using SQL, such as an index, a package, a procedure, a table, a trigger, a view, or an XSR object. See also database object, invalid object.
In object-oriented design or programming, an abstraction that consists of data and operations associated with that data.

object type

A categorization or grouping of object instances that share similar behaviors and characteristics.

occasionally connected

In SQL replication, pertaining to a replication configuration that contains target servers that are not always connected to the network. Using this configuration, users can connect to a primary data source for a short time to synchronize their local databases with the data at the source.

ODBC

See Open Database Connectivity.

ODBC driver

A dynamically linked library (DLL) that implements ODBC function calls and interacts with a data source.

offline backup

A backup of the database or table space that is made while the database or table space is not being accessed by applications. During an offline backup, the backup database utility acquires exclusive use of the database until the backup is complete. See also online backup.

offline maintenance

Maintenance activities that can occur only when user access to a database is interrupted. See also online maintenance.

OLAP

See online analytical processing.

OLTP

See online transaction processing.

online analytical processing (OLAP)

The process of collecting data from one or many sources; transforming and analyzing the consolidated data quickly and interactively; and examining the results across different dimensions of the data by looking for patterns, trends, and exceptions within complex relationships of that data.

online backup

A backup of the database or table space that is made while the database or table space is being accessed by other applications. See also offline backup.

online index reorganization

The reorganization of indexes on a table while the table and existing indexes are available for reading and updating by concurrent transactions.

online maintenance

Maintenance activities that can occur while users are connected to a database. See also offline maintenance.

online table move

A method for moving data in a table to a new table in the same database, in which the original table remains accessible for select, insert, update, and delete operations. The table is offline for only a few seconds at the end of the online move operation.

online transaction processing (OLTP)

A type of interactive application in which requests that are submitted by users are processed as soon as they are received. Results are returned to the requester in a relatively short period of time.

Open Database Connectivity (ODBC)

A standard application programming interface (API) for accessing data in both relational and nonrelational database management systems. Using this API, database applications can access data stored in database management systems on a variety of computers even if each database management system uses a different data storage format and programming interface. See also Java Database Connectivity.

operand

An entity on which an operation is performed.

operational data

Data that is used to run the day-to-day operations of an organization.

operator

In an access plan for an SQL or XQuery statement, a token that specifies the type of action that must be performed on data or on the output from a table or an index when the access plan is executed.

optimistic concurrency control

See optimistic locking.

optimistic locking

A locking strategy whereby no lock is held between the time that a row is selected and the time that an update or a delete operation is attempted on that row. See also currently committed, pessimistic locking.

optimization guideline

An instruction to the query optimizer on how to choose a query execution plan. See also global optimization guideline, optimization profile, statement optimization guideline.

optimization profile

An XML document that contains optimization guidelines for one or more DML statements. An optimization profile is used to provide explicit guidelines to the query optimizer when the performance of DML statements is not acceptable and other tuning options are ineffective. See also optimization guideline.

optimized SQL text

SQL text, produced by the Explain facility, that is based on the query actually used by the optimizer to choose the access plan. This query is supplemented and rewritten by the various components of the SQL compiler during statement compilation. The text is reconstructed from its internal representation and differs from the original SQL text. The optimized statement produces the same result as the original statement.

ordering mode

In DB2 XQuery, a mode, either ordered or unordered, that affects the ordering of the result sequence that is returned by path expressions, union expressions, intersect expressions, and except expressions and by FLWOR expressions that do not have an order by clause.

ordinal position

The position associated with each element in an array. The ordinal position is an integer value greater than or equal to 1 and less than or equal to n, where n is the cardinality.

ordinary array

An array with a defined upper boundary on the number of elements, which are referenced by their ordinal position in the array. See also array, associative array, element.

ordinary identifier

An uppercase letter followed by zero or more characters, each of which is an uppercase letter, a number, or the underscore character. An ordinary identifier should not be a reserved word.

ordinary token

A numeric constant, an ordinary identifier, a host identifier, or a keyword.

originating task

The primary agent in a parallel group that receives data from other execution units (referred to as parallel tasks) that are executing portions of the query in parallel.

orphaned contact

A contact that exists in the health notification contact list but is not defined in the contact list that is stored on the system that is specified by the CONTACT_HOST configuration parameter of the DB2 administration server. See also contact.

outer join

A join method in which a column that is not common to all of the tables being joined becomes part of the resultant table.
A join whose result consists of the matched rows of the two tables that were joined and the unmatched rows of one or both tables. See also full outer join, inner join, join, left outer join, right outer join.

outline

The structure that defines all elements of a database within the DB2 OLAP Server. For example, an outline contains definitions of dimensions, members, and formulas.

output file

A database or device file that is opened with the option to allow records to be written.

ownership privilege

A control privilege that allows all privileges for the owned data object.

P

package

In Java programming, a group of types. Packages are declared with the package keyword. (Sun)
In PL/SQL programming, a collection of database objects that is defined by using a CREATE PACKAGE statement and represented as a module. See also module.
A control-structure database object produced during program preparation that can contain both executable forms of static SQL statements or XQuery expressions and placement holders for executable forms of dynamic SQL statements.

package cache

A cache that stores package, statement, and section information required for the execution of dynamic and static SQL statements. This cache improves overall system performance by reducing invocations of the SQL compiler and the need to access the system catalogs. See also statement cache.

package name

The name of an object that is created by the BIND, PRECOMPILE, or REBIND command. The object is a bound version of a database request module (DBRM). The name consists of a location name, a collection ID, a package ID, and a version ID.

packet

In data communication, a sequence of binary digits, including data and control signals, that are transmitted and switched as a composite whole.

page

In a graphical interface, a predefined display image that typically provides fields and controls that help users accomplish tasks.
In DB2 for IBM i, a block of storage within a table or an index.
In DB2 for Linux, UNIX, and Windows and DB2 for z/OS, a unit of storage within a table space, an index space, or virtual memory. In a table space, a page can contain one or more rows of a table. In an LOB table space, an LOB value can span more than one page, but no more than one LOB value is stored on a page.

page set

A table space or index space that consists of a collection of VSAM data sets. See also table space.

page set recovery pending (PSRCP)

A restrictive state of an index space in which the entire page set must be recovered. Recovery of a logical part is prohibited.

panel

A formatted display of information on a screen that can also include entry fields.

panic

A condition in which the kernel stops executing correctly and hangs, stops, or crashes, usually as a result of an unrecoverable error.

parallel I/O processing

The process of reading from or writing to two or more I/O devices at the same time to reduce response time.
A form of I/O processing in which DB2 for z/OS initiates multiple concurrent requests for a single user query and performs I/O processing concurrently (in parallel) on multiple data partitions.

parallelism

The ability to perform multiple database operations at the same time.

parameterized cursor

A cursor with a result set defined by a set of user-specified parameters and a query that references the parameters. When the cursor is opened, the parameter values and the query are used to generate the cursor result set. See also cursor.

parameterized data type

A data type that can be defined with a specific length, scale, or precision. For example, string and decimal data types are parameterized.

parameter marker

In the statement string of a dynamic SQL statement, a placeholder that represents a value that will be provided by the application program. The value of a parameter marker is provided on the EXECUTE or OPEN statement associated with the dynamic SQL statement. A parameter marker can be used where a host variable might be used if the statement string were a static SQL statement. A parameter marker is either a question mark (?) or a colon followed by a name (:name). See also host variable, typed parameter marker, untyped parameter marker.

parameter name

An identifier that names a parameter that can be referenced in a procedure or user-defined function.

parametric search

A search that looks for objects that contain a numeric value or attribute (such as dates, integers, or other numeric data types) within a specified range.

parent activity

An activity whose processing results in the launching of a child activity. For example, a procedure becomes a parent activity as it opens a cursor, which becomes the child activity. See also child activity.

parent key

A primary key or unique key that is used in a referential constraint. The values of a parent key determine the valid values of the foreign key in the constraint.

parent row

A row that has at least one dependent row. See also dependent row.

parent table

A table that is a parent in at least one referential constraint. See also dependent foreign key table, dependent table.

parent table space

A table space that contains a parent table. A table space containing a dependent of that table is a dependent table space. See also dependent.

partial declustering

The storage of table data on a named subset of database partitions (database partition group), rather than on all database partitions for the database.

participant

An entity other than the commit initiator that takes part in the commit process.

partition

A portion of a page set. Each partition corresponds to a single, independently extendable data set. Partitions can be extended to a maximum size of 1, 2, or 4 gigabytes, depending on the number of partitions in the partitioned page set. All partitions of a given page set have the same maximum size.

partition-compatible join

A join where all of the rows that are joined are in the same database partition. See also collocated join.

partitioned database environment

A database installation that supports distribution of the data across database partitions.

partitioned data set (PDS)

A data set on direct access storage that is divided into partitions, called members, each of which can contain a program, part of a program, or data. See also sequential data set.

partitioned index

An index that is physically partitioned. Both partitioning indexes and secondary indexes can be partitioned. See also index partition, nonpartitioned index, partitioned table.

partitioned table

A table whose rows are physically stored in data partitions according to a table-partitioning key. See also nonpartitioned table, partitioned index.

partitioned table space

A table space that is subdivided into parts (based on index key range), each of which can be processed independently by utilities.

partitioning agent

The process that distributes data to the database partitions. See also load agent, pre-partitioning agent.

partitioning key

See distribution key.

partitioning map

See distribution map.

pass-through mode

A mode through which SQL statements can be submitted directly to a data source.

pass-through session

A DB2 session used to submit SQL statements directly to a database management system (DBMS) using the SQL dialect associated with that data source.

path

In a network environment, the route between any two nodes.
The route through a file system to a specific file.

path expression

An XQuery expression that navigates through a node hierarchy by a series of steps to select nodes for further processing. See also node test, step.

PC/IXF

A file format that is an adaptation of the Integration Exchange Format (IXF), which was specifically designed to enable the exchange of relational database structures and data. The PC/IXF file architecture maintains the independence of both the exporting and the importing database systems.

PDS

See partitioned data set.

peer state

In high availability disaster recovery, the state during which the primary database ships new log pages from its in-memory log buffer to the standby database when the same log pages are written to the log disk of the primary database. See also asynchronous mode, near synchronous mode, remote catchup state, super asynchronous mode.

peer-to-peer replication

A replication configuration between logical tables in which updates to any table are replicated to the other tables and convergence is maintained. Peer-to-peer replication can involve two or more servers. See also multi-tier replication, update-anywhere replication.

performance snapshot

Performance data for a set of database objects that is retrieved from the database manager at a point in time. See also explain snapshot.

performance variable

A statistic derived from performance data obtained from the database manager. The expression for this variable can be defined by the user.

period

In a table, an interval of time that is defined by two datetime columns. A period contains a begin column and an end column. See also begin column, end column.

permanent table space

A table space that can store any persistent data. See also large table space, regular table space.

per-member database configuration parameter

A database configuration parameter that can have its value applied only to a single member.

personal certificate

The digital certificate that a client or server gives to other clients or servers as a means of authentication. A personal certificate is usually obtained from a certificate authority.

pessimistic locking

A locking strategy whereby a lock is held between the time that a row is selected and the time that a searched update or delete operation is attempted on that row. See also currently committed, optimistic locking.

phantom row

A table row that can be read by application processes that are executing with any isolation level except repeatable read. When an application process issues the same query multiple times within a single unit of work, additional rows can appear between queries because of the data being inserted and committed by application processes that are running concurrently.

physical consistency

The state of a page that is not in a partially changed state.

physical data model

In DB2 data warehousing, a metadata model that represents the tables and other objects in a database.

physical index

A component of a user-defined index over XML data. A physical index contains generated columns, which are keys that support the logical index, and it also contains the indexed document values. See also logical index.

piece

A data set of a nonpartitioned page set.

plan allocation

The process of allocating DB2 for z/OS resources to a plan in preparation to execute it.

PL/SQL

See Procedural Language SQL.

PLT

See program list table.

plug-in

A dynamically loadable library that a DB2 database management system uses to carry out user-written actions that involve the database.

point-in-time table

In SQL replication, a type of replication target table whose content matches all or part of a source table, with an added column that identifies the approximate time when a particular row was inserted or updated at the source system.

point of consistency

A time when all of the recoverable data that a program accesses is consistent. The point of consistency occurs when updates, insertions, and deletions are either committed to a physical database or rolled back. See also roll back.

port

To modify a computer program that runs on a given system to enable it to run on a different system.

postponed abort UR

A unit of recovery that was inflight or in-abort, was interrupted by system failure or cancellation, and did not complete backout during restart.

power user

A person who has special privileges to perform object management tasks, such as creating and updating objects.

precision

An attribute of a number that describes the total number of binary or decimal digits.
An attribute of a timestamp that describes the total number of decimal digits in the fractional seconds part of the value.

precompile

To process programs that contain SQL statements before they are compiled. SQL statements are replaced with statements that will be recognized by the host language compiler. The output from a precompile process includes source code that can be submitted to the compiler and used in the bind process.

predicate

An element of a search condition that expresses or implies a comparison operation.

preferred primary cluster caching facility

The cluster caching facility that the cluster manager attempts to start as the primary cluster caching facility when a DB2 pureScale instance is started. See also cluster caching facility, primary cluster caching facility.

prefetch

To read data ahead of, and in anticipation of, its use.

prepare

To convert an SQL statement or XQuery expression from text form to an executable form, by submitting it to the SQL and XQuery compiler.

prepared SQL statement

A named object that is the executable form of an SQL statement that was processed by the PREPARE statement.

prepared XQuery expression

A named object that is the executable form of an XQuery expression that was processed by the PREPARE statement.

prepare phase

The first phase of a two-phase commit process in which all participants are requested to prepare for commit.

pre-partitioning agent

The process that reads data and distributes it to the partitioning agent. See also load agent, partitioning agent.

primary authorization ID

The authorization identifier used to identify an application process to DB2 for z/OS. See also secondary authorization ID.

primary cluster caching facility

The cluster caching facility that is currently handling requests from the members in an instance. See also cluster caching facility, preferred primary cluster caching facility, secondary cluster caching facility.

primary database

In high availability disaster recovery, the main database, which is accessed by applications. Applications apply updates to the primary database, and those updates are propagated on the standby database by using log shipping.

primary expression

The basic primitive structure of the XQuery language. Primary expressions include literals, variable references, context item expressions, constructors, and function calls. A primary expression can also be created by enclosing any expression in parentheses, which can help to control the precedence of operators.

primary index

An index that enforces the uniqueness of a primary key.

primary key

In a relational database, a key that uniquely identifies one row of a database table. See also constraint, foreign key, unique key.

primary log

A set of one or more log files that are used to record changes to a database and for which storage is allocated in advance. See also secondary log.

primary reintegration

The process in which the original primary database can rejoin a high availability disaster recovery pair after a failover. The original primary database can rejoin only as the new secondary database in the HADR pair.

principal HADR standby database

In an HADR multiple standby system, the standby database that allows any synchronization mode. Only one principal HADR standby database can be defined in a multiple standby system. See also auxiliary HADR standby database, standby database.

principal standby database

See principal HADR standby database.

private key

In secure communication, an algorithmic pattern used to encrypt messages that only the corresponding public key can decrypt. The private key is also used to decrypt messages that were encrypted by the corresponding public key. The private key is kept on the user system and is protected by a password. See also key, public key.

private sort

A sort that takes place in the agent private memory of a database agent. See also agent private memory.

privilege

The right to access a specific database object in a specific way. A privilege is controlled by users with access control (ACCESSCTRL) or security administrator (SECADM) authority or by users who have the privilege and the ability to grant it to others. Privileges can include rights to create, delete, and retrieve data from tables.
The capability of performing a specific function, sometimes on a specific object. See also authority level, authorization.

Procedural Language SQL (PL/SQL)

The Oracle implementation of a language that provides procedural constructs for implementing control flow logic around traditional SQL queries and operations. See also SQL Procedural Language.

procedure

A routine that can be invoked using the SQL CALL statement to perform operations that can include both host language statements and SQL statements. See also built-in procedure, external procedure, routine, SQL procedure, user-defined procedure.

procedure body

The implementation of the logic of a procedure. See also routine body.

processing instruction

An embedded directive within an XML instance document that is passed to an application when the document is parsed. The processing instruction node is one of the kinds of nodes that are defined in the XQuery and XPath data model. See also node kind.

processing time

For a thread or an agent performing work in a monitored time interval, the amount of elapsed time minus the amount of wait time. See also elapsed time, wait time.

program list table (PLT)

A CICS control table that contains a list of programs that can run as a group during CICS startup or shutdown and can be enabled and disabled as a group by a single CEMT transaction.

progressive streaming

A method of retrieving a LOB or an XML value from a database server in the most optimal manner by using Dynamic Data Format. See also Dynamic Data Format.

projected coordinate system

In DB2 Spatial Extender, a reference system that defines locations on a planar surface.

promote

To copy replication definitions for subscription sets or registered sources from one database to another database, without registering the sources again or creating the subscription sets again.

propagation

A process in which groups of configuration parameters are updated and take effect at different rates.

property

A characteristic or attribute that describes a unit of information.

protected column

In label-based access control, a column to which access is limited with a security label.

protected row

In label-based access control, a row to which access is limited with a security label.

protected table

In label-based access control, a table that contains at least one row or one column to which access is limited with a security label.

proximity search

A text search that returns a result when two search patterns occur within a specified distance from each other.

pruning

In data replication, the process of removing obsolete data from objects such as control tables, staging tables, or queues.

pseudodeleted

Pertaining to a key that is marked as deleted but has not yet been physically removed from the index page. See also pseudoempty.

pseudoempty

Pertaining to an index page on which all the keys are marked as pseudo deleted. See also pseudodeleted.

PSRCP

See page set recovery pending.

public alias

An alias defined in the SYSPUBLIC schema that can always be referenced by its unqualified name without any impact from the current default schema name. See also alias.

publication

In event publishing, an object that identifies what changes are published from a source table to a user application. The Q Capture program publishes changes from a source table and puts those changes on a send queue in XML or delimited format. See also Q subscription, replication source.

public key

In secure communication, an algorithmic pattern used to decrypt messages that were encrypted by the corresponding private key. A public key is also used to encrypt messages that can be decrypted only by the corresponding private key. Users broadcast their public keys to everyone with whom they must exchange encrypted messages. See also key, private key.

public synonym

See public alias.

published module object

A database object defined in a module that can be referenced from outside the module. See also module object.

publishing queue map

In event publishing, an object that contains the settings for how a Q Capture program processes transactions and identifies the WebSphere MQ queue that is used to send transactional data. See also event publishing, queue map, replication queue map.

pull configuration

In SQL replication, a configuration in which the Apply program runs on the target server. The Apply program pulls updates from the source server to apply them to the target. See also push configuration.

pureXML

A DB2 feature in which the representation of the data from client to disk and back (that is, both the logical and physical data models) is XML.

push configuration

In SQL replication, a configuration in which the Apply program runs on the source server or a replication server other than the target server. The Apply program pushes updates from the source server to apply them to the target. See also pull configuration.

pushdown

In a federated system, the processing of fragments of a query at a data source instead of at the federated system. See also compensation.

Q

Q Apply latency

In Q replication, an approximate measurement of the difference between the time that the Q Apply program gets changed data from the receive queue and the time that the data is applied to a target table. This measurement is a subset of the end-to-end latency in a replication scenario. See also Apply latency, Capture latency, end-to-end latency, latency, Q Capture latency, queue latency.

Q Apply program

In Q replication, a program that reads transactions from a receive queue and applies those changes to one or more target tables or passes the changes to a procedure.

Q Apply schema

In Q replication, the identifier for a Q Apply program and its control tables.

Q Apply server

In Q replication, a database or subsystem on which the control tables for the Q Apply program are located and where the Q Apply program runs. It contains one or more sets of the control tables that store information about target tables and other replication definitions.

Q Capture latency

In Q replication, an approximate measurement of how current a Q Capture program is in reading the DB2 database recovery log. This measurement is the approximate difference between the time that source data was changed and the time that the Capture program made the data available by committing it to WebSphere MQ. This measurement is a subset of the end-to-end latency in a replication scenario. See also Apply latency, Capture latency, end-to-end latency, latency, Q Apply latency, queue latency.

Q Capture program

In Q replication and event publishing, a program that reads the DB2 database recovery log to capture changes made to DB2 database source tables and transmits the changes by using one or more WebSphere MQ queues. See also Capture program, event publishing, Q replication.

Q Capture schema

In Q replication, the identifier for a Q Capture program and its control tables.

Q Capture server

In Q replication and event publishing, a database or subsystem on which the control tables for the Q Capture program are located and where the Q Capture program runs. The Q Capture server contains one or more sets of the control tables that store information about Q subscriptions, publications, and other replication or publishing objects. See also control server.

Q Capture transaction latency

In Q replication, the time between when a Q Capture program reads the commit statement for a transaction in the DB2 database recovery log and when the Q Capture program puts the message that contains the transaction on a send queue.

QName

See qualified name.

Q replication

A replication solution that uses WebSphere MQ message queues for high-volume, low-latency replication. See also high availability disaster recovery, Q Capture program, SQL replication.

QSAM

See queued sequential access method.

Q subscription

In Q replication, an object that identifies a mapping between a source table and target table or procedure and specifies what changes are replicated. See also publication, replication source, subscription.

qualified name (QName)

A name that conforms to the Namespaces in XML specification. A QName consists of an optional prefix, or its associated URI, and a local name. See also expanded QName, in-scope namespace.

quantified predicate

A predicate that compares a value with a set of values.

quantile

A subgroup that is created when a group is divided into equal, ordered parts.

query

A component of certain SQL or XQuery statements that specifies a result set.
A request for information from a database that is based on specific conditions: for example, a request for a list of all customers in a customer table whose balances are greater than USD1000.

query block

The part of a query that is represented by one of the FROM clauses. Each FROM clause can have multiple query blocks, depending on how DB2 for z/OS processes the query.

query body

The part of a query that contains the XQuery expression. See also query prolog.

query CP parallelism

Parallel execution of a single query, which is accomplished by using multiple tasks.

query I/O parallelism

Parallel access of data, which is accomplished by triggering multiple I/O requests within a single query.

query optimization class

A set of query rewrite rules and optimization techniques for compiling queries.

query optimizer

A component of the SQL and XQuery compiler that chooses an access plan for a data manipulation language statement by modeling the execution cost of many alternative access plans and choosing the one with the minimal estimated cost. See also compensation.

query prolog

In DB2 XQuery, a series of declarations that defines the processing environment for a query. See also query body.

query statement

See query.

queue

A line or list of items waiting to be processed, for example, work to be performed or messages to be displayed or transmitted.
An object that holds messages for message-queueing applications. A queue is owned and maintained by a queue manager.

queued sequential access method (QSAM)

An access method for storing and retrieving logical records in a continuous sequence. Input data blocks awaiting processing or output data blocks awaiting transfer to auxiliary storage are queued on the system to minimize delays in I/O operations.

queue latency

In Q replication and event publishing, an approximate measurement of the difference between the time that the Q Capture program commits data to WebSphere MQ and the time that WebSphere MQ makes the data available to the Q Apply program or a receiving application. Queue latency is a subset of the end-to-end latency in a replication scenario or an event publishing scenario. See also end-to-end latency, Q Apply latency, Q Capture latency.

queue map

In Q replication and event publishing, an object that contains the settings for how Q replication and event publishing programs process transactions and identifies the WebSphere MQ queues that are used in a replication or event publishing scenario. See also publishing queue map, replication queue map.

quiesce

To end a process or shut down a system after allowing normal completion of active operations.

quiesced

Pertaining to the state of an instance or database when it has no active transactions, the buffer pools are flushed, no new transactions are allowed, and no new connections are allowed.

quiesce point

A point at which data is consistent as a result of running the DB2 QUIESCE utility.

quoted name

See delimited identifier.

R

RACF

See Resource Access Control Facility.

range-clustered table (RCT)

A table whose data is tightly clustered across one or more columns. Each record in the table has a predetermined offset from the logical start of the table, which allows rapid access to the data.

RBA

See relative byte address.

RCT

See range-clustered table.

RDB

See relational database.

RDBMS

See relational database management system.

RDF

See Resource Description Framework.

RDF store

A set of tables that store an RDF data set. See also Resource Description Framework.

RDS

See Relational Data Services.

read access state

A state indicating that only read access to a table is allowed.

readahead prefetching

A method of prefetching pages by looking ahead in a scan, which results in asynchronous retrieval of pages even though those pages are not located sequentially on disk.

read-only

Pertaining to data that can be read but cannot be modified.

read stability (RS)

An isolation level under which a query that is issued more than once in a transaction is guaranteed to read the same rows for each subsequent execution. However, in subsequent executions, the query might read additional (phantom) rows that were inserted or updated and then committed by statements in concurrently running transactions. A query in a transaction using RS is prevented from reading any rows changed by statements in other transactions until the changes have been committed. Also, until the transaction using RS has been committed, any rows that a query in that transaction reads cannot be changed by statements in other transactions. See also cursor stability, isolation level, repeatable read, uncommitted read.

real-time replication

See synchronous replication.

rebind

To create a package for an application program by using information from the previously bound package. For example, in DB2 for Linux, UNIX, and Windows and DB2 for z/OS, if an index is added for a table that is accessed by a program, the package must be rebound for it to take advantage of the new index. See also automatic rebind, explicit rebind, implicit rebind, recompile.

rebuild

To restore a database or a subset of its table spaces by using a set of table space restore operations.

rebuild phase

The stage that a database is in from the time that the database successfully completes a rebuild restore operation until the first time that the database is rolled forward and log records start being processed.

recapture

In update-anywhere replication, to capture changes at a replica table and forward these changes to the master table or to other replica tables.

receive queue

In Q replication, a WebSphere MQ message queue that is used by a Q Apply program to receive transactions that are captured by a Q Capture program.

recompile

To re-create a package for an application program by using information in the application program code. See also rebind.

record identifier (RID)

A unique identifier that the DB2 database manager uses internally to identify a row of data in a table.

recording

The information from performance snapshots that can be viewed at a later time.

record length

The total length of all the columns in a table. The record length is the length of the data as physically stored in the database. Records can be fixed or variable in length, depending on how the columns are defined. If all columns are fixed-length columns, the record is a fixed-length record. If one or more columns are varying-length columns, the record is a varying-length record.

recovery

The process of re-creating a database or table space that became unusable because of hardware failure, software failure, or both. The process includes restoring a backup image and can also include rolling database logs forward in time.

recovery log

See database log.

recovery pending (RECP)

The state of a database or table space when it is restored from a backup. While the database or table space is in this state, its data cannot be accessed.

RECP

See recovery pending.

recursion cycle

The cycle that occurs when a fullselect within a common table expression includes the name of the common table expression in a FROM clause.

recursive common table expression

A common table expression that refers to itself in a FROM clause from the fullselect. Recursive common table expressions are used to write recursive queries.

recursive query

A fullselect that uses a recursive common table expression.

redo

A state of a unit of recovery that indicates that changes are to be reapplied to the disk media to ensure data integrity.

referential constraint

The requirement that the nonnull values of a designated foreign key are valid only if they are also values of the primary key of the parent table. The referential constraint is always defined from the perspective of the dependent file. See also constraint.

referential cycle

A set of referential constraints such that each table in the set is a descendent of itself.

referential integrity

The state of a database in which all values of all foreign keys are valid. Maintaining referential integrity requires the enforcement of a referential constraint on all operations that change the data in a table where the referential constraints are defined.

referential structure

A set of tables and relationships such that for every table in the set, the set includes all relationships in which that table participates and all the tables to which it is related.

regions index

An internal, system-generated index associated with an XML column that represents how an XML document is divided into regions.

register

In SQL replication, to define a DB2 table, view, or nickname as a replication source.

registration

In SQL replication, the process of registering a DB2 table, view, or nickname as a replication source. See also subscription.

registration process

In replication, the process of defining a replication source.

regular table space

A table space that stores persistent data in either database-managed space or system-managed space but that has a smaller space limit than that of a large table space. See also permanent table space.

rejected transaction

A transaction that contains one or more updates from replica tables that are in conflict with the master table.

related view

A view that uses, or is dependent on, another object, such as the parent view of a table.

relational cube

A set of data and metadata that defines a multidimensional database. A relational cube is the portion of a multidimensional database that is stored in a relational database.

relational database (RDB)

A database that can be perceived as a set of tables and manipulated in accordance with the relational model of data. Each database includes a set of system catalog tables that describe the logical and physical structure of the data, a configuration file containing the parameter values allocated for the database, and a recovery log with ongoing transactions and archivable transactions.

relational database management system (RDBMS)

A collection of hardware and software that organizes and provides access to a relational database.

Relational Data Services (RDS)

The component of the DB2 database manager that processes requests to access or manipulate the contents of a database. For SQL requests, RDS processing involves translating statement text into an executable section, running that section, and returning the result set to the requester.

relational schema

See SQL schema.

relationship

A defined connection between the rows of a table or the rows of two tables. A relationship is the internal representation of a referential constraint.

relative byte address (RBA)

The offset of a data record or control interval from the beginning of the storage space that is allocated to the data set or file to which it belongs.

relative path

A path that begins with the current working directory. See also absolute path.

remote catchup state

In high availability disaster recovery, the state of the standby database after it reads all of the existing local log files. The database remains in this state until it establishes a connection with the primary database. See also peer state.

remote database

A database to which a connection is made by using a database link, while connected to a local database. See also local database.

remote request

A request issued from an agent at one database partition to an agent at a different database partition. See also request.

remote unit of work (RUOW)

A unit of work that lets a user or an application program read or update data at one location per unit of work. RUOW supports access to one database within a unit of work. An application program can update several remote databases, but it can access only one database within a unit of work. See also unit of work.

reoptimization

The process of reconsidering, at run time, the access path of an SQL statement that has already been optimized. During reoptimization, the actual values of host variables, parameter markers, and special registers might be considered in choosing the access path.

REORG pending (REORP)

A condition that restricts SQL access and most utility access to an object that must be reorganized.

REORG-recommended operation

An operation that changes the format of the data that is written to permanent storage for a table and restricts the operations that are allowed on the table until the data in the table is reorganized.

REORP

See REORG pending.

repeatable read (RR)

An isolation level under which a query that is issued more than once in a transaction reads the same rows again for each subsequent execution, except for rows that might have been changed earlier in the same transaction. Additional (phantom) rows are not read. A query in a transaction using RR is prevented from reading any rows changed by statements in other transactions until the changes have been committed. Also, until the transaction using RR has been committed, any rows that a query in that transaction reads cannot be changed by statements in other transactions. See also cursor stability, isolation level, read stability, uncommitted read.

replay

To apply the contents of a database log to a standby database, such as during a recovery operation.

replica table

In SQL replication, specifically in update-anywhere replication, a type of target table that can be updated locally and also receives updates from the master table through a subscription-set definition. If replication conflict detection is enabled, changes made to the replica table are rejected, whereas changes made to the master table are retained. See also conflict detection, master table, update-anywhere replication.

replication

The process of maintaining a defined set of data in more than one location. Replication involves copying designated changes for one location (a source) to another (a target) and synchronizing the data in both locations.

replication administrator

In SQL replication and in Q replication, the user who is responsible for registering replication sources and creating subscription sets. This user can also run the Capture program and the Apply program.

Replication Alert Monitor

A program that checks the operation of the Capture, Apply, Q Capture, and Q Apply programs and sends alerts to one or more users when it detects the specified alert conditions.

Replication Analyzer

A program that can analyze a replication environment for setup problems, configuration errors, and performance issues.

Replication Center

A graphical interface that can be used to define, operate, maintain, and monitor the replication environment.

replication control table

A table in which replication definitions or control information is stored.

replication queue map

In Q replication, an object that links a send queue and a receive queue. The replication queue map includes settings for how a Q Capture program processes all transactions that use the send queue and how a Q Apply program processes all transactions that use the receive queue. See also publishing queue map, queue map.

replication source

In SQL replication, a table, view, or nickname that is registered as a source for replication. Changes that are made to this table, view, or nickname are captured and copied to a target table that is defined in a subscription-set member. See also subscription set, subscription-set member.
In Q replication, a table that is a source for replication. Changes made to this type of table are captured and copied to a target table that is defined in a Q subscription or a publication. See also publication, Q subscription.

replication subscription

See subscription set.

replication target

In Q replication and in SQL replication, a table or procedure that is a destination for changes that were replicated from a source. The Q Apply program applies these changes. See also target table.

request

A directive to perform a discrete action within a database system. A request is acted upon by a database agent. See also application request, remote request, subagent request.

requester

The source of a request to access data at a remote server.

reserved word

A word that has been set aside for special use in the SQL standard.
A word that is defined by a programming language and that cannot be used as an identifier or changed by the user.

resident member

A fully functional member that runs on its home host and that can accept a database connection from an external application. See also guest member, member.

resource

The object of a lock or claim, which can be a table space, an index space, a data partition, an index partition, or a logical partition.

Resource Access Control Facility (RACF)

An IBM licensed program that provides access control by identifying users to the system; verifying users of the system; authorizing access to protected resources; logging unauthorized attempts to enter the system; and logging accesses to protected resources.

resource allocation

The part of plan allocation that deals specifically with database resources.

Resource Description Framework (RDF)

A framework for representing information on the web. See also RDF store.

resource manager

In an XA-enabled environment, software that manages and provides access to shared resources, such as databases. The DB2 database system is an example of a resource manager.

response file

An ASCII file that can be customized with the setup and configuration data that automates an installation. During an interactive installation, the setup and configuration data must be entered, but with a response file, the installation can proceed without any intervention.

response file generator

A utility that creates a response file from an existing installed and configured DB2 product. The generated response file can be used to re-create the same setup on other computers.

restart light

The act of restarting a member on a host other than its home host for the sole purpose of performing member crash recovery on each database as required. See also guest member.

restart pending (RESTP)

A restrictive state of a page set or partition that indicates that restart (backout) work must be performed on the object.

restart queue

A local queue that holds restart information for each send queue that a Q Capture program uses. The Q Capture program uses the information to determine where to start reading in the DB2 recovery log after a restart.

restore

To rebuild a damaged or corrupted database or table space from a backup image produced with the backup database utility.

restore set

A backup copy of a database or table space plus zero or more log files that, when restored and rolled forward, bring the database or table space back to a consistent state.

RESTP

See restart pending.

result set

A set of row values as returned by, for example, a cursor or procedure. See also result table.

result set locator

A value used by a DB2 application to uniquely identify a query result set returned by a procedure.

result table

The set of rows produced by the evaluation of a SELECT statement. See also base table, result set, temporary table.

retention-limit pruning

In SQL replication, the pruning of CD and unit-of-work tables by the Capture program that are older than a limit that the user specifies.

reverse data type mapping

In a federated system, the mapping of a DB2 data type to a comparable data type at a remote data source. For most data sources, the default reverse data type mappings are in the wrappers. See also data type mapping, forward data type mapping.

revoke

To remove a privilege or an authority from an authorization identifier.

rework

In replication, an action that is taken when an SQL statement fails against a target table and the resulting SQL return code indicates that another SQL statement could be used to produce the expected result in the target table. An example is the conversion of an insert into a replication target table to an update if the insert fails because the row exists in the target table. Another example is the conversion of an update to a replication target table to an insert if the update fails because the row does not exist in the target table.

RID

See record identifier.

RID list

A list of all of the RIDs that correspond to all of the rows that share a given index key. For example, if three rows share an index key, the RID list for that index key contains the RIDs for all three rows.

right

See privilege.

right outer join

A join whose result consists of the matched rows of the two tables that were joined and the unmatched rows of the second table. See also full outer join, join, left outer join, outer join.

role

A database entity that groups together one or more privileges and that can be assigned, for example, to users, PUBLIC, other roles, or trusted contexts.

roll back

To restore data that is changed by an SQL statement to the state at its last commit point. See also backout, point of consistency, roll forward.

roll forward

To update the data in a restored database or table space by applying changes recorded in the database log files. See also roll back.

rollforward operation

The process of updating the data in a restored database or table space by applying changes recorded in the database log files.

rollforward recovery

A process that is used to recover a database by applying transactions that were recorded in the database recovery log file. See also crash recovery, version recovery.

rollout

The efficient deletion of a large portion of a multidimensional clustering (MDC) table, which is possible when a DELETE statement is processed that either has no predicates or certain types of predicates (equality, range, BETWEEN, IN) on one or more dimension columns. See also deferred index cleanup rollout, immediate index cleanup rollout.

root CA

See root certificate authority.

root certificate authority (root CA)

The certificate authority at the top of the hierarchy of authorities by which the identity of a certificate holder can be verified.

root installation

An installation performed by the root user.

root instance

A DB2 instance created by the root user from the DB2 product installed by that user.

root node

The common ancestor of all nodes in a set of nodes. There is only one root node for each XML instance document.

root page

The index page that is at the highest level (or the beginning point) in an index.

root user

A system user who operates without restrictions. A root user has the special rights and privileges needed to perform administrative tasks.
In Linux and UNIX operating systems, a user who has superuser authority and root privileges. A root user's user identifier (UID) is 0.

rotating diagnostic log

A diagnostic log file that grows to a limited size, after which it is closed and a new diagnostic log file is created and opened for logging. To create the name of the new file, the index number used in the file name is incremented by 1.

round-robin

Pertaining to an operation in which the database manager provides a continuous, even distribution of data within memory, across data partitions, or across storage containers.

routine

A database object that can encapsulate procedural logic and SQL statements, is stored on a database server, and can be invoked using an SQL statement such as the CALL statement. The three main classes of routines are procedures, functions, and methods. See also aggregate function, built-in function, built-in procedure, external routine, function, method, procedure, row function, scalar function, sourced function, SQL function, SQL method, SQL procedure, SQL routine, table function, user-defined function, user-defined procedure.

routine body

The implementation of the logic of a routine. See also function body, method body, procedure body, routine prototype.

routine prototype

The definition of a module routine without a routine body. A routine prototype can be referenced in an SQL statement; however, the referenced routine can be successfully invoked only after its routine body has been defined. See also module, routine body.

row

The horizontal component of a table, consisting of a sequence of values, one for each column of the table.

row-begin column

A generated column that is defined with the AS ROW BEGIN clause. The value is assigned whenever a row is inserted into the table or any column in the row is updated. A row-begin column is intended for use as the first column of a SYSTEM_TIME period. See also generated column, row-end column, transaction-start-ID column.

row blocking

See blocking.

row-capture rule

In SQL replication, a rule that determines whether the Capture program captures changes for all columns or for registered columns only.

row change timestamp column

A generated column that is defined with the AS ROW CHANGE TIMESTAMP clause. A row change timestamp column provides a way for the database manager to automatically generate and maintain a timestamp value for each row that is inserted or updated in a table. A table can have no more than one row change timestamp column.

row-end column

A generated column that is defined with the AS ROW END clause. The value is assigned whenever a row is inserted into the table or any column in the row is updated. A row-end column is intended for use as the second column of a SYSTEM_TIME period. See also generated column, row-begin column, transaction-start-ID column.

row function

An SQL function that optionally accepts arguments and that returns a single row of values. A row function can be implemented in SQL and used as a transform function to map attributes of a structured type to built-in data type values in a row. See also function, routine.

rowid

A value that uniquely identifies a row in a table and does not change.

row lock

A lock on a single row of data. See also table lock.

row-positioned access

The ability to retrieve a single row by using a single FETCH statement. See also rowset-positioned access.

rowset

A set of rows for which a cursor position is established.

rowset cursor

A cursor that is defined so that one or more rows can be returned as a rowset for a single FETCH statement and the cursor is positioned on the set of rows that is fetched.

rowset-positioned access

The ability to retrieve multiple rows by using a single FETCH statement. See also row-positioned access.

row trigger

A trigger whose granularity is defined by using the FOR EACH ROW clause.

row variable

A global variable, local variable, or parameter of a row data type.

RR

See repeatable read.

RS

See read stability.

RUOW

See remote unit of work.

S

satellite

A DB2 database server that is a member of a group of similar DB2 database servers. Each satellite in the group runs the same application and has a similar configuration to support the application. See also DB2 control server.

satellite control server

A DB2 database system that contains the satellite control database, SATCTLDB.

savepoint

A named entity that represents the state of data and schemas at a particular point in time within a unit of work.

savepoint level

A distinct scope that is used for reference and for interaction between savepoint-related statements.

SBCS

See single-byte character set.

SCA

See shared communications area.

scalar fullselect

A fullselect that returns a single value: one row of data that consists of exactly one column. See also fullselect.

scalar function

An SQL function that optionally accepts arguments and that returns a single scalar value each time that it is invoked. A scalar function can be referenced in an SQL statement wherever an expression is valid. See also function, routine.

scale

The number of digits in the fractional part of a number.

scan sharing

The ability of multiple scans to share the same buffer pool content.

scan throttling

The process of slowing down a scan to ensure that its pages in the buffer pool are not purged and remain available for sharing with other scans.

scattered read

A method of reading contiguous data pages from disk to discontiguous portions of memory. See also block-based I/O.

schema

See XML schema.
See SQL schema.

score

In DB2 Text Search and DB2 Net Search Extender, an absolute value of 0 - 1 of type DOUBLE that indicates how well a document meets the search criteria relative to the other found documents. The value indicates the number of matches in the document relative to the size of the document.
In data mining, to apply a data mining model to new data, such as to perform predictions or segmentations.

scrollability

A property of a cursor that indicates whether the cursor can fetch in a backward direction. See also fetch orientation.

scrollable cursor

A cursor that can be used to fetch in backward and forward directions. See also nonscrollable cursor.

scrollable result set

A result set that is associated with a scrollable cursor that allows the application to fetch rows and to refetch previously fetched rows.

SDK

See software development kit.

search

To request the display of objects that meet user-specified criteria.

search argument

The conditions specified when searching, consisting of one or several search terms and search parameters.

search condition

A criterion for selecting rows from a table. A search condition consists of one or more predicates.

secondary authorization ID

In DB2 for z/OS, an authorization identifier that is associated with a primary authorization ID by an authorization exit routine. See also primary authorization ID.

secondary cluster caching facility

A standby for the primary cluster caching facility. A secondary cluster caching facility takes over as the primary cluster caching facility if the primary cluster caching facility fails or must be taken offline. See also cluster caching facility, primary cluster caching facility.

secondary index

A nonpartitioning index on a partitioned table. See also nonpartitioned index.

secondary log

A set of one or more log files used to record changes to a database when the primary log is full. See also primary log.

section

The segment of a plan or package that contains the executable structures for a single SQL statement. See also SQL and XQuery compiler.

section actuals

Runtime statistics gathered during execution of the section for an access plan.

Secure Sockets Layer (SSL)

A security protocol that provides communication privacy. With SSL, client/server applications can communicate in a way that is designed to prevent eavesdropping, tampering, and message forgery. See also certificate authority.

security administrator

An individual who is responsible for managing security within a database.

security label

In label-based access control (LBAC), a database object that can be granted to users and can also be applied to columns and rows in a table to protect the data. Only users who are granted appropriate security labels can access data that is protected by a security label. See also label-based access control, security label component, security policy.

security label component

In label-based access control, a database object that represents one of the criteria that an organization uses to decide who has access to specific data. See also element, security label.

security policy

In label-based access control, a database object that is associated with one or more tables and that defines how LBAC can be used to protect those tables. The security policy defines what security labels can be used, how the security labels are compared to each other, and whether optional behaviors are used. See also label-based access control, security label.

segment

A group of pages that holds a row of a single table.

segmentation violation

An error caused when a program attempts to access memory not allocated to it.

segmented table space

A table space that is divided into equal-sized groups of pages called segments. Segments are assigned to tables so that rows of different tables are never stored in the same segment.

self-referencing constraint

A referential constraint that defines a relationship in which a table is a dependent of itself.

self-referencing row

A row that is a parent of itself.

self-referencing table

A table that is both a parent and a dependent table in the same referential constraint.

send queue

In Q replication, a WebSphere MQ message queue that is used by a Q Capture program to publish transactions that it has captured. A send queue can be used either for Q replication or event publishing, but not both at the same time.

sensitive cursor

A cursor whose result table is affected by changes made to a database after the result table has been materialized. See also cursor, cursor sensitivity.

sensitivity

The amount of time by which a threshold-based health indicator must exceed its threshold or the amount of time that a state-based health indicator must be in a non-normal state before an alert is generated.

sequence

A database object that is independent of any one table that automatically generates unique key values based on initial user specifications.
In the XQuery and XPath data model, an ordered collection of zero or more items. See also XQuery and XPath data model.

sequence type

A data type that can be expressed by using the SequenceType syntax, which describes the type of an XQuery value. Sequence types are used to refer to a data type in an XQuery expression.

sequential data set

A data set whose records are organized based on their successive physical positions, such as on magnetic tape. See also partitioned data set.

sequential prefetch

A mechanism that triggers consecutive asynchronous I/O operations. Pages are fetched before they are required, and several pages are read by using a single I/O operation.

serial cursor

See nonscrollable cursor.

serialization

In Q replication, the process of applying transactions in the same order in which they were committed at the source.
The consecutive ordering of items.
The process of controlling access to a resource to protect the integrity of the resource.

serialize

To convert an XML value into a character string or binary string form. This process is the inverse of parsing.

serialized profile

A Java object, one or more of which are produced by the SQLJ translator, that contains SQL statements and descriptions of host variables. A serialized profile file is used to describe the SQL statements so that they can be run with either a JDBC-based or a customized runtime library.

serialized XML

An XML value in the form of a character string or binary string. See also XML data.

server

The target of a request from a remote requester. In a DB2 database system, the server function is provided by the distributed data facility, which is used to access a DB2 database from remote applications.
A software program or a computer that provides services to other software programs or other computers. See also client, host.

server definition

In a federated system, the name and information that define the data source to the federated database.

server name

An identifier that designates an application server. In a federated system, the server name also designates the local name of a data source. See also alias, database name.

service class

An entity that acts as a point of resource control and monitoring for a set of database connections and activities within a DB2 database. There are two levels of service classes: service superclass and service subclass. See also service subclass, service superclass, workload definition.

service name

A name that provides a symbolic method of specifying the port number to be used at a remote node. To identify an application, the TCP/IP connection requires the address of the remote node and the port number to be used on the remote node.

service subclass

A grouping mechanism for database activities within a service superclass. Resources of a service superclass are shared by all related service subclasses. See also service class, service superclass.

service superclass

A grouping mechanism for connections within a database. See also service class, service subclass.

session

A logical or virtual connection between two stations, software programs, or devices on a network that allows the two elements to communicate and exchange data for the duration of the session. See also SQL connection, transaction.

session global variable

A global variable whose value is shared only within the session where it exists. See also database global variable, global variable.

set integrity pending

A state indicating that integrity processing is required on a table. To remove this state, a SET INTEGRITY statement must be processed for the table. See also check pending, integrity processing.

set integrity pending no access state

A state indicating that integrity processing is required for a table and that no access to that table is allowed until integrity processing is complete.

set integrity pending read access state

A state indicating that integrity processing is required for a table and that only read access to that table is allowed until integrity processing is complete.

set operator

The SQL operators UNION, EXCEPT, and INTERSECT, which correspond to the relational operators union, difference, and intersection. A set operator derives a result table by combining two other result tables.

shadow index

In index reorganization, an internal structure that is built and then used for index access after the index reorganization is complete.

shadowing

A recovery technique in which current page contents are never overwritten. Instead, new pages are allocated and written while the pages whose values are being replaced are retained as shadow copies to support system restoration. The shadow copies are deleted when they are no longer needed.

shared communications area (SCA)

A memory structure in a cluster caching facility that can be simultaneously accessed by multiple members in a DB2 pureScale instance. The SCA contains database-wide control data that must be synchronized across all members.
A coupling facility list structure that a DB2 for z/OS data sharing group uses for communication between members of the data sharing group.

shared lock

A lock that limits concurrently running application processes to read-only operations on database data. See also exclusive lock, gross lock.

shared-nothing environment

A distributed database architecture in which each database partition server has its own processor, memory, and disks.

sharing group

A collection of agents that scan the same object, such as a table, using the same mechanism, such as a table scan, and potentially share pages or records of this object that are in the buffer pool.

sharing set

A collection of sharing groups that access the same object, such as a table, using the same mechanism, such as a table scan.

shift-in character (SI)

A control character (X'0F') that is used in EBCDIC systems to denote that the subsequent bytes represent single-byte character set (SBCS) characters. See also shift-out character.

shift-out character (SO)

A control character (X'0E') that is used in EBCDIC systems to denote that the subsequent bytes, up to the next shift-in control character, represent double-byte character set (DBCS) characters. See also shift-in character.

shredding

See decomposition.

shutdown

The process of ending operation of a system or a subsystem by following a defined procedure.

SI

See shift-in character.

signal

In replication, an SQL statement that allows communication with the Capture program and the Q Capture program. A signal is inserted into the signal control table and received by the Capture program or the Q Capture program when the program reads the log entry for the signal insert.

signaling NaN (sNaN)

In decimal floating-point operations, a value, not interpreted as a mathematical value, that contains a mask and a sequence of floating-point digits and that causes an invalid operation condition if used in certain arithmetic operations. See also decimal floating-point number.

signer certificate

The digital certificate that validates the issuer of a certificate. For a CA, the signer certificate is the root CA certificate. For a user who creates a self-signed certificate for testing purposes, the signer certificate is the user's personal certificate. See also truststore.

significand

The significant digits of a floating-point number.

sign-on

A request made by an application process or terminal user to verify authorization to use resources.

simple table space

A table space that is neither partitioned nor segmented.

single-byte character set (SBCS)

A coded character set in which each character is represented by a 1-byte code. A 1-byte code point allows representation of up to 256 characters. See also double-byte character set, multibyte character set.

single-partition database environment

A database server with all instances, databases, and logical database partitions on one computer.

single-precision floating point number

A 32-bit approximate representation of a real number. See also floating-point number.

slice

The set of blocks that contains pages with data having a certain value of one of the clustering dimensions.

slot directory

An array of byte-offset locations at which index keys are located on an index page.

SMP

See symmetric multiprocessor.

SMS

See storage management subsystem.

SMS table space

See system-managed space table space.

sNaN

See signaling NaN.

snapshot

A record of the current state of the database environment.

SO

See shift-out character.

SOAP

A lightweight, XML-based protocol for exchanging information in a decentralized, distributed environment. SOAP can be used to query and return information and invoke services across the Internet. See also web service.

socket

A communications handle used by TCP/IP.

soft checkpoint

The process of writing information to the log file header; this information is used to determine the starting point in the log in case a database restart is required.

soft CPU shares

An attribute that defines the relative share of CPU resources on a host or LPAR that the WLM dispatcher allows a particular service class to use and exceed when additional CPU resources are available.

soft invalidation

A process whereby access to a dependent object is allowed to continue after an object on which it depends was dropped or modified by a DDL statement. The next explicit reference to the dependent object that requires the dynamic SQL cache to be accessed causes the dependent object to be recompiled.

software development kit (SDK)

A set of tools, APIs, and documentation to assist with the development of software in a specific computer language or for a particular operating environment.

sourced function

A function that duplicates the semantics of another function, called a source function. Only scalar and aggregate functions can be sourced functions. See also function, routine, user-defined function.

source program

A set of host language statements and SQL statements that is processed by an SQL precompiler.

source server

A database or subsystem that contains the source tables for replication.

source table

A table that contains data that is to be replicated to a target table. See also target table.

source type

An existing type that is used to internally represent a distinct type.

spatial column

A column in a table that is defined using one of the spatial data types provided by DB2 Spatial Extender.

spatial data

Data that is made up of coordinates that identify a geographic location or geographic region.

spatial function

A function provided by DB2 Spatial Extender that performs various operations on spatial data.

spatial reference system

In DB2 Spatial Extender, a set of parameters that includes coordinates that define the maximum possible extent of space that is referenced by a given range of coordinates, an identifier of the coordinate system from which the coordinates are derived, and numbers that convert coordinates into positive integers to improve performance when the coordinates are processed.

special character

A non-alphabetic and non-numeric character, such as %, &, /, ?, ], and a number of other characters that have a unique function in the SQL language.

special register

A storage area that is defined for an application process by the database manager and is used to store information that can be referenced in SQL statements. Examples are USER and CURRENT DATE. See also built-in global variable, global variable.

spill file

In SQL replication, a temporary file that the Apply program creates to hold data for updating target tables.

spill queue

In Q replication, a dynamic queue that the Q Apply program creates to hold transactions that occur at the source table while a target table is being loaded. The Q Apply program later applies these transactions and then deletes the spill queue.

SQL

See Structured Query Language.

SQL and XQuery compiler

A DB2 component that analyzes the semantics of an SQL or XQuery statement and produces an efficient executable form of the statement. See also section.

SQL authorization ID (SQL ID)

In DB2 for z/OS, the ID that is used for checking the authorization of dynamic SQL statements in some situations.

SQLCA

See SQL communication area.

SQL communication area (SQLCA)

A set of variables that provides an application program with information about the execution of its SQL statements, XQuery expressions, or requests from the database manager.

SQL connection

An association between an application process and a local or remote application server or database server. See also connection, session.

SQLDA

See SQL descriptor area.

SQL data change statement

An SQL statement, such as the INSERT, UPDATE, DELETE, or MERGE statement, that is used to change data in user tables.

SQL descriptor area (SQLDA)

A set of variables in a structure used in the processing of certain SQL statements that describe input variables, output variables, or the columns of a result table. The SQLDA is intended for dynamic SQL programs.

SQL function

A function that is implemented entirely by using a subset of SQL statements and SQL procedural language (SQL PL) statements. See also function, routine, user-defined function.

SQL ID

See SQL authorization ID.

SQLJ

See Structured Query Language for Java.

SQL method

A method that is implemented entirely by using a subset of SQL statements and SQL PL statements. See also method, routine.

SQL path

An ordered list of schema names that is used to resolve unqualified references to user-defined functions, distinct types, and procedures.

SQL PL

See SQL Procedural Language.

SQL Procedural Language (SQL PL)

A language extension of SQL that consists of statements and language elements that can be used to implement procedural logic in SQL statements. SQL PL provides statements for declaring variables and condition handlers, assigning values to variables, and for implementing procedural logic. See also Procedural Language SQL.

SQL procedure

A user-written program that is implemented entirely by using a subset of SQL statements and SQL PL statements and that is invoked by using the SQL CALL statement. See also built-in procedure, procedure, routine, SQL routine, user-defined procedure.

SQL replication

A type of replication that uses staging tables. See also Q replication, staging table.

SQL return code

The SQLSTATE or SQLCODE value that indicates whether the previously run SQL statement completed successfully, with one or more warnings, or with an error.

SQL routine

A function, method, or procedure that has its routine logic implemented entirely with SQL statements and SQL PL language elements and statements. See also routine, SQL procedure.

SQL schema

A collection of database objects such as tables, views, indexes, functions, user-defined types, or triggers that defines a database. An SQL schema provides a logical classification of database objects.

SQL statement

A complete instruction to the database manager that is written using SQL.

SQL statement coprocessor

An alternative to the DB2 for z/OS precompiler that can be used to process SQL statements at compile time. The user invokes an SQL statement coprocessor by specifying a compiler option.

SQL/XML

A section of the ISO Database Languages - SQL standard that defines XML-related functionality in SQL that allows SQL statements to construct, manipulate, and query XML data.

SQL/XML constructor

A function that creates XML structures or typed atomic values within an SQL statement.

SSL

See Secure Sockets Layer.

SSL server authentication

A type of authentication that allows a client to confirm the identity of a server. SSL-enabled client software uses standard techniques of public-key cryptography to ensure that the certificate and public ID of a server are valid and that the certificate and ID were issued from one of the client's trusted certificate authorities (CAs). See also certificate, certificate authority.

stack

An area in memory that typically stores information such as temporary register information, values of parameters, and return addresses of subroutines and is based on the principle of last in, first out (LIFO).

staging table

In SQL replication, a consistent-change-data table that is used to save data before that data is replicated to the target database. A consistent-change-data table used for staging data can function as an intermediate source for updating data in one or more target tables. See also consistent-change-data table, SQL replication.

stand-alone

Pertaining to a program that can run separately from the DB2 database system, without using DB2 services.

stand-alone text search server

The Enterprise Content Management text search server that is installed with the DB2 Accessories Suite for use with a DB2 server.

standard database

In high availability disaster recovery, a database that is neither the primary nor the standby. A standard database is not configured for high availability disaster recovery. See also high availability disaster recovery.

standby database

In high availability disaster recovery, a copy of the primary database. Updates to this database occur by rolling forward log data that is generated on the primary database and sent to the standby database. See also auxiliary HADR standby database, high availability disaster recovery, principal HADR standby database.

star join

A method of joining a dimension column of a fact table to the key column of the corresponding dimension table. See also dimension table, fact table, join, star schema.

star schema

A type of relational database schema that is composed of a set of tables comprising a single, central fact table surrounded by dimension tables. See also dimension table, star join.

stash file

A file that stores an encrypted version of the key database password. See also key database, key file.

statement cache

The portion of the package cache related to dynamic SQL statements. See also package cache.

statement concentrator

A mechanism that modifies dynamic SQL statements at the database server so that SQL statements with similar but not identical text can share the same access plan. The modified and original statements produce the same results.

statement handle

The data object that contains information about an SQL statement or XQuery expression that is managed by the DB2 call level interface. Such information includes dynamic arguments, bindings for dynamic arguments and columns, cursor information, result values, and status information. Each statement handle is associated with a connection handle. See also connection handle.

statement optimization guideline

An optimization guideline that applies to a single DML statement. See also optimization guideline.

statement string

The character string form of a dynamic SQL statement.

statically known namespaces

In XQuery, a set of prefix and URI pairs that defines all of the namespaces that are known during static processing of an expression. Statically known namespaces are a component of the static context of an expression.

static context

The information that is available during compilation of an XQuery expression before the expression is evaluated. See also dynamic context, expression context.

static cursor

A named control structure that does not change the size of the result table or the order of its rows after an application opens the cursor. See also cursor, dynamic cursor.

static IP address

A fixed IP address for a persistent device or logical unit on a network that uses the IP standard. See also IP address.

static SQL

SQL statements that are embedded within a program and are bound before the program is executed. After being bound, a static SQL statement does not change, although values of host variables specified by the statement can change. See also deferred embedded SQL, dynamic SQL, embedded SQL, incremental bind statement.

statistical view

A view for collecting statistics that the query optimizer uses to obtain the most appropriate access plan.

statistics profile

A file that contains all of the option information that specifies which statistics are collected for a table when using a particular RUNSTATS command.

step

A part of an XQuery path expression that generates a sequence of items and then filters the sequence by zero or more predicates. The value of the step consists of those items that satisfy the predicates. See also node test, path expression.

stop word

A word that is commonly used, such as "the," "an," or "and," that is ignored by a search application.

stop word removal

The process of removing stop words from the query to ignore common words and return more relevant results.

storage group

A named set of storage paths on which DB2 for Linux, UNIX, and Windows data can be stored.
A named set of disks on which DB2 for z/OS data can be stored.

storage management subsystem (SMS)

Software that automates as much as possible the management of physical storage by centralizing control, automating tasks, and providing interactive controls for system administrators.

storage protection key

A hardware key associated with each page of virtual memory that is available in POWER6 processors and is supported as of AIX Version 5.3 with the 5300-06 Technology Level. Access to pages is controlled on a per-thread basis depending on the access mode of the running thread as represented in the authority mask register (AMR). See also authority mask register.

stored procedure

See procedure.

string

The value of a character string, graphic string, or binary string data type, consisting of a sequence of bytes that might represent characters.
In programming languages, the form of data used for storing and manipulating text.

string delimiter

A symbol that is used to enclose a string constant. The SQL string delimiter is the apostrophe (') except in COBOL applications, where the user assigns either a quotation mark (") or an apostrophe (').

strong dependency

A dependency that causes an object to be recompiled when another object that it depends on, such as a table or a data type, is dropped or modified. See also weak dependency.

strongly typed cursor data type

A cursor data type that is associated with a row data type. A variable or parameter of a strongly typed cursor data type can reference only a result set with the same definition as the row data structure. See also weakly typed cursor data type.

strongly typed distinct type

A distinct type that restricts most operations in which the data types of the operands are not the same distinct type. See also distinct type, weakly typed distinct type.

strong typing

A process that prevents two objects with mismatched data types from being compared to each other and prevents data from being assigned to an object defined to accept data of a different type. See also implicit casting, weak typing.

structure

A name that refers collectively to different types of DB2 objects, such as tables, databases, views, indexes, and table spaces.

Structured Query Language (SQL)

A standardized language for defining and manipulating data in a relational database. See also Data Manipulation Language.

Structured Query Language for Java (SQLJ)

A standard for embedding SQL in Java programs, defining and calling Java procedures and user-defined functions, and using database structured types in Java.

subagent

An agent that the coordinator agent enlists to speed up SQL processing. See also coordinating agent.

subagent request

A request issued by a coordinator agent to a subagent at the same or a different database partition. See also request.

subcomponent

A group of closely related DB2 for z/OS modules that work together to provide a general function.

subject table

The table for which a trigger is created. When the defined triggering event occurs on this table, the trigger is activated.

subnormal number

In floating-point representation, any nonzero number that is smaller than the smallest normal number. A subnormal number has zero as the leftmost digit of the significand. See also decimal floating-point number, normal number.

subordinate agent

See subagent.

subquery

A form of a fullselect that is enclosed within parentheses and used as a component of a query.

subscribe

In SQL replication, to enable tables or views registered as replication targets to receive initial source data and subsequent changes from tables or views registered as replication sources.

subscription

In SQL replication, an object that creates subscription sets and subscription-set members. See also Q subscription, registration, subscription set.

subscription cycle

The process in which the Apply program retrieves changed data for a given subscription set, replicates the changes to the target table, and updates the appropriate replication control tables to reflect its status and current progress.

subscription set

In SQL replication, a definition that controls the replication of changed data during a subscription cycle. A subscription set can contain zero or more subscription-set members. See also replication source, subscription.

subscription-set member

In SQL replication, a definition that maps a registered replication source to a replication target. Each member defines the structure of the target table and the rows and columns that are replicated from the source table. See also replication source.

subselect

The form of a query that does not include a UNION, INTERSECT, or EXCEPT operator. Subselect query syntaxes can differ depending on the platform.

subset

To replicate data from part of a source table, rather than from the entire table, to a target table. Data can be subset by rows or by columns.

substitution character

A unique character that is substituted during character conversion for any characters in the source program that do not have a match in the target coding representation.

subsystem

In z/OS, a service provider that performs one or many functions but does nothing until a request is made. For example, each WebSphere MQ for z/OS queue manager or instance of a DB2 for z/OS database management system is a z/OS subsystem.

success code set

One or more expressions that specify the return codes of a successful task. For example, > -1 can be specified to consider all return codes of zero or more a success.

summary table

A materialized query table whose fullselect contains a GROUP BY clause that summarizes data from the tables referenced in the fullselect. See also materialized query table.

super asynchronous mode

In high availability disaster recovery, the synchronization mode in which the primary database considers a transaction committed when the transaction is successfully written to the disk of the primary system. The primary database does not wait for an acknowledgment that the log data was sent to the standby system. See also high availability disaster recovery, peer state, synchronization mode.

superuser

A user who has various system control authorities above and beyond that of the ordinary user. In UNIX environments, the standard superuser is root.

Support Assistant

See IBM Support Assistant.

surrogate pair

A coded representation for a single character that consists of a sequence of two 16-bit code units, in which the first value of the pair is a high-surrogate code unit in the range U+D800 through U+DBFF, and the second value is a low-surrogate code unit in the range U+DC00 through U+DFFF. Surrogate pairs provide an extension mechanism for encoding an additional 1,048,576 characters without using any 32-bit code units.

symmetric multiprocessor (SMP)

A system in which functionally identical multiple processors are used in parallel, providing simple and efficient load balancing.

synchpoint

In SQL replication, a control table value for the sequence number in the DB2 log or journal record corresponding to the last change that was applied during the most recent Apply cycle. This value is also used to coordinate the pruning of CD tables. See also change-data table.

synchronization

The process by which a satellite downloads and runs the same DB2 database commands, operating system commands, and SQL statements from the satellite control server as the other members of its group download and then reports the results to the satellite control server.

synchronization mode

In high availability disaster recovery, an option that specifies the level of coordination between the primary and standby databases when logs are sent from the primary database to the standby database in peer state. Synchronization mode determines the balance between performance and the potential for data loss. See also asynchronous mode, near synchronous mode, super asynchronous mode, synchronous mode.

synchronous

Pertaining to two or more processes that depend upon the occurrences of specific events, such as a common timing signal. See also asynchronous.

synchronous mode

In high availability disaster recovery, the synchronization mode in which the primary database considers a transaction to be committed when it gets an acknowledgment message from the standby system that confirms that the relevant log data was received and written to disk on the standby system. See also synchronization mode.

synchronous replication

A type of replication that delivers updates continuously and within the scope of source transactions. See also asynchronous replication.

sync point

See point of consistency.

synonym

See alias.

synonym dictionary

A dictionary that enables users to search for synonyms of their query terms when they search a collection.

syscall

See system call.

system administrator

A DB2 database user with administrative authority. In DB2 for Linux, UNIX, and Windows and in DB2 for z/OS, this authority is SYSADM. In DB2 for IBM i, this authority is *ALLOBJ.

system authority

An authority level that has full privileges for managing a system but cannot access the data in the system. The system authority level can be SYSCTRL or SYSMAINT. See also authority level.

system call (syscall)

A call by a program to an operating system subroutine.

system catalog

See catalog.

system conversation

The conversation that two DB2 for z/OS subsystems must establish to process system messages before any distributed processing can begin.

system database directory

A directory that contains entries for every database that can be accessed by using the database manager. The directory is created when the first database is created or cataloged on the system. See also local database directory.

system-managed space table space (SMS table space)

A table space whose storage space is managed by the file system manager of the operating system. This storage model is based on files that are created under subdirectories and are managed by the file system. See also database-managed space table space.

system monitor

See database system monitor.

system period

A pair of columns with system-maintained values that indicates the period of time when a row is valid. See also system-period data versioning, system-period temporal table.

system-period data versioning

Automatic maintenance of historical data by the database manager by using a system period. See also system period, system-period temporal table.

system-period temporal table

A table that is defined with system-period data versioning. See also bitemporal table, history table, system period, system-period data versioning.

system temporary table space

A temporary table space that stores system temporary tables. A system temporary table space is created by default when a database is created. See also temporary table space.

system time

The amount of time that the operating system spends providing services to an application. System time includes time spent by the operating system allocating storage or devices to a program and time spent processing operating system calls that a program makes. See also execution time, user time.

T

table

In a relational database, a database object that consists of a specific number of columns and is used to store an unordered set of rows. See also base table, temporary table, view.

table check constraint

See check constraint.

table collocation

In a partitioned database environment, a state that occurs when two tables that have the same number of compatible partitioning keys are stored in the same database partition group. In this situation, the DB2 database management system can perform the join or subquery processing at the database partition where the data is stored.

table-controlled partitioning

A type of partitioning in which partition boundaries for a partitioned table are controlled by values that are defined in the CREATE TABLE statement.

table designator

An exposed name used to qualify a column name. See also exposed name.

table expression

An expression that creates a temporary result table from a query. For example, a table expression might be a query that selects all of the managers from several departments and further specifies that they have over 15 years of working experience and are located at the main branch.

table function

A function that receives a set of arguments and that returns a table to the SQL statement that references the function. A table function can be referenced only in the FROM clause of a subselect. See also function, routine, user-defined function.

table lock

A lock on a table of data. See also row lock.

table-mode processing

In SQL replication, a type of replication subscription-set processing in which the Apply program retrieves all of the data from the source CD table, applies the data (one member at a time) to each target table, and finally commits its work. See also transaction-mode processing.

table object ID

Internal logical identifier for a table. In DB2 for Linux, UNIX, and Windows, table object IDs for each table in a database are stored in the TABLEID column of the SYSCAT.TABLES catalog view.

table partitioning

A data organization scheme in which table data is divided across multiple data partitions according to values in one or more partitioning columns of the table. Data from a given table is partitioned into multiple storage objects, which can be in different table spaces, based on the specifications that are provided in the PARTITION BY clause of the CREATE TABLE statement. See also data partition, database partitioning.

table-partitioning key

An ordered set of one or more columns whose values are used to determine in which data partition each table row belongs. See also data partition, database partition, distribution key.

table queue

A mechanism for transferring rows between database partitions. Table queues are distributed row streams with simplified rules for the insertion and removal of rows. Table queues can also be used to deliver rows between different processes in a single-partition database.

table space

A logical unit of storage in a database. In DB2 for z/OS, a table space is a page set and can contain one or more tables. In DB2 for Linux, UNIX, and Windows, a table space is a collection of containers, and the data, index, long field, and LOB portions of a table can be stored in the same table space or in separate table spaces. See also container, page set.

table space container

An allocation of space to a table space. Depending on the table space type, the container can be a directory, device, or file.

table space ID

Internal logical identifier for the primary table space for an object. In DB2 for Linux, UNIX, and Windows, table space IDs for each table space in a database are stored in the TBSPACEID column of the SYSCAT.TABLES catalog view.

table space set

A set of table spaces and partitions that should be recovered together because the tables contained in the table spaces have dependencies on one another. The dependencies can, for example, be between parent table and descendent table or between base table and auxiliary table.

tag

In markup languages such as SGML, XML, and HTML, a token representing the start or end of an element.

target

The destination for an action or operation.

target server

In Q replication and SQL replication, a database or subsystem that contains replication target tables or procedures.

target table

In Q replication, a table that is the destination for replicated changes from a source that is part of a Q subscription.
In SQL replication, a table that is the destination for changes from a registered replication source. A target table can be a user copy table, a point-in-time table, a base aggregate table, a change aggregate table, a CCD table, or a replica table. See also Apply program, replication target, source table.

TCP/IP

See Transmission Control Protocol/Internet Protocol.

TCP/IP port

A 2-byte value that identifies a TCP/IP network application within a TCP/IP host.

temporal table

A table that records the period of time when a row is valid.

temporary table

A table that holds temporary data. Temporary tables are useful for holding or sorting intermediate results from queries that contain many rows. The two kinds of temporary tables, which are created by different SQL statements, are the created temporary table and the declared temporary table. See also base table, created temporary table, declared temporary table, result table, table.

temporary table space

A table space that can store only temporary data. See also system temporary table space, user temporary table space.

territory

A portion of the POSIX locale that is mapped to the territory code for internal processing by the database manager.

territory code

A code that is used by the DB2 database manager to preset the default collation order for an SBCS database and to establish monetary, date, time, and numeric formatting that is specific to a country, region, or territory.

tessellation

The division of a surface into a mesh or network.

text index

In DB2 Net Search Extender, a collection of significant terms extracted from text documents. Each term is associated with the document from which it was extracted.

text search index

In DB2 Text Search, a collection of significant terms extracted from text documents. Each term is associated with the document from which it was extracted.

text search index collection

The smallest unit of a text search index that is managed by the text search server.

text search index partition

The collection that contains the text search index data from a specific database partition. A text search index is mapped to one or more collections to match the distribution of the data table that hosts the text index.

textual XML format

A representation of XML data that uses character values, an approach that allows for direct reading by people.

thread

The DB2 structure that describes the connection of an application, traces its progress, processes resource functions, and delimits its accessibility to DB2 resources and services. Most DB2 functions execute under a thread structure.

threadsafe

Pertaining to a function, macro, or operating system service that can be called from multiple threads in a process at the same time.

three-part name

The full name of a table, view, or alias that consists of a location name, an authorization identifier, and an object name, separated by periods.

threshold

A user-defined entity that establishes a condition or boundary that, if exceeded, causes the data server to take a prescribed set of actions. See also workload definition.

threshold definition domain

The object that a threshold is associated with and whose activities are monitored to ensure that the threshold condition is not exceeded. A threshold affects only activities within its domain.

threshold enforcement scope

The area for which a threshold is both monitored and enforced for activities to which the threshold has been applied. Examples of this area include a workload occurrence, a database partition, or a database.

throttled utility

A utility that has a limit placed on the resources that would otherwise be consumed. The degree to which the resources are limited is based on the current workload of the system. Supported utilities include backup, restore, and table space reorganization.

time

A three-part value that designates a time of day in hours, minutes, and seconds. See also timestamp.

time-based update detection

A means of determining when rows were last updated, using the ROW CHANGE TIMESTAMP expression.

time duration

A DECIMAL (6,0) value that represents a number of hours, minutes, and seconds.

timeout

Abnormal termination of either an application or the DB2 for z/OS subsystem because of the unavailability of resources.

timeron

A unit of measurement used to give a rough relative estimate of the resources required, or the cost, for the database server to execute two plans for the same query. The resources calculated in the estimate include weighted processor and I/O costs.

timestamp

A seven-part value that consists of date and time. The timestamp is expressed in years, months, days, hours, minutes, seconds, and fractional seconds. See also date, time.

timestamp duration

A DECIMAL (20,6) value that represents a number of years, months, days, hours, minutes, seconds, and microseconds.

Tivoli Space Manager

A feature of the Tivoli Storage Manager product that handles the moving of files in and out of a secondary storage medium based upon actual file accesses in the primary native file system. This feature can be used with DB2 Data Links Manager to enable DATALINK files to be stored in a virtually infinitely sized file system.

Tivoli Storage Manager

A client/server product that provides storage management and data access services in a heterogeneous environment. Tivoli Storage Manager supports various communication methods, provides administrative facilities to manage the backup and storage of files, and provides facilities for scheduling backups.

TM database

See Transaction Manager database.

token

The basic syntactic unit of a computing language. A token consists of one or more characters, excluding the blank character and excluding characters within a string constant or delimited identifier.

trace

In DB2 replication, a facility that is used to collect monitoring, auditing, and performance data for the Capture program, the Q Capture program, the Apply program, the Q Apply program, or the Replication Alert Monitor.

transaction

An atomic series of SQL statements that make up a logical unit of work. All of the data modifications made during a transaction are either committed together as a unit or rolled back as a unit.
An exchange between two programs that carries out an action or produces a result. An example is the entry of a customer's deposit and the update of the customer's balance. See also conversation, session.

transaction-based replication

In SQL replication, a type of processing in which every transaction is replicated to the target table when it is committed in the source table. See also transaction-consistent replication.

transaction-consistent replication

In SQL replication, a type of processing in which the net result of all transaction updates is replicated to the target table. See also transaction-based replication.

transaction manager

A function that assigns identifiers to transactions, monitors their progress, and takes responsibility for transaction completion and failure recovery.

Transaction Manager database (TM database)

A database that is used to log transactions when a two-phase commit (SYNCPOINT TWOPHASE) is used with DB2 databases. If a transaction fails, the TM database information can be accessed to resynchronize databases that were involved in the failed transaction.

transaction-mode processing

In SQL replication, a type of replication subscription-set processing in which the Apply program retrieves data from the source CD table, then applies the data to the target table in the same commit sequence that is used at the source. The Apply program processes transactions for all subscription-set members together, rather than sequentially. See also table-mode processing.

transaction-start-ID column

A generated column that is defined with the AS TRANSACTION START ID clause. The value is assigned whenever a row is inserted into the table or any column in the row is updated. A transaction-start-ID column is intended for use in a system-period temporal table. See also generated column, row-begin column, row-end column.

transform

A collection of installation-related changes that are applied to a Windows Installer database.

transform function

A function that is used to exchange structured data type values in one direction between a DB2 server and host language programs.

transform group

A set of transform functions that is used to exchange structured data type values between a DB2 server and host language programs.

transition table

A temporary table that contains all of the affected rows of a subject table in their state before or after a triggering event occurs. Triggered SQL statements in the trigger definition can reference the table of changed rows in the old state or the new state.

transition variable

A variable that is valid only in FOR EACH ROW triggers. It allows access to the transition values for the current row. An old transition variable is the value of the row before the modification is applied, and the new transition variable is the value of the row after the modification is applied.

Transmission Control Protocol/Internet Protocol (TCP/IP)

An industry-standard, nonproprietary set of communication protocols that provides reliable end-to-end connections between applications over interconnected networks of different types.

transparent DDL

DDL that provides the ability to create and modify remote tables in a federated database without using pass-through sessions.

transport

To restore a transportable set from a backup image into a database other than the one from which the backup image was taken.
A physical connection to a database. A transport can be reused by multiple logical connections.

transportable set

A set of table spaces and schemas that can be transported by a restore operation, such as by the RESTORE DATABASE command.

transport staging database

A temporary database that is created as a part of a transport operation. The transport staging database is used to extract data and logical objects from a backup image and, if necessary, bring them to a point of transactional consistency before they are re-created in the target database.

trap

An unprogrammed, hardware-initiated, conditional jump to a specific address. A trap occurs as a result of an error or certain other conditions. A record is made of the location from which the jump occurred.

tree view

A view that provides a hierarchical view of an object and the objects that it contains.

trigger

A database object that is associated with a single base table or view and that defines a rule. The rule consists of a set of SQL statements that runs when an insert, update, or delete database operation occurs on the associated base table or view. See also after trigger, before trigger, delete trigger, insert trigger, instead of trigger, trigger activation, trigger activation time, trigger granularity, update trigger.

trigger activation

The process that occurs when the trigger event that is defined in a trigger definition is executed. Trigger activation consists of the evaluation of the triggered action condition and conditional execution of the triggered SQL statements. See also after trigger, before trigger, trigger, trigger activation time, trigger event.

trigger activation time

An indication in a trigger definition of whether the trigger should be activated before or after a trigger event. See also after trigger, before trigger, trigger, trigger activation, trigger event.

trigger body

The set of triggered SQL statements that is run when a trigger is activated and its triggered action condition evaluates to true. See also triggered action, triggered action condition, triggered SQL statement.

trigger cascading

The process that occurs when the triggered action of a trigger causes the activation of another trigger.

triggered action

The SQL logic that is performed when a trigger is activated. The triggered action consists of an optional triggered action condition and a set of triggered SQL statements that is run only if the triggered action is true. See also trigger body, trigger event, triggered action condition, triggered SQL statement.

triggered action condition

An optional part of a triggered action. This Boolean condition is defined by a WHEN clause and specifies a condition that is evaluated to determine whether the triggered SQL statements should be run. See also trigger body, triggered action, triggered SQL statement.

triggered SQL statement

One of a set of SQL statements that is run when a trigger is activated and its triggered action condition evaluates to true. The set of triggered SQL statements is also called the trigger body. See also trigger body, triggered action, triggered action condition.

trigger event

In a CREATE TRIGGER statement, the specification of an insert, update, or delete operation on a specified table that activates the trigger. See also trigger activation, trigger activation time, trigger granularity, triggered action.

trigger granularity

In SQL, the characteristic of a trigger that determines whether the trigger is activated only once for the triggering SQL statement or once for each row that the SQL statement modifies. See also trigger, trigger event.

triggering SQL operation

The SQL operation that causes a trigger to be activated when the operation is performed on the subject table.

trigger package

In DB2 for z/OS, a package that is created when a CREATE TRIGGER statement is executed. The package is executed when the trigger is activated.

truncation

The process of discarding part of a result from an operation when it exceeds memory or storage capacity.

trust attribute

An attribute upon which to establish trust. A trusted relationship is established based on one or more trust attributes.

trusted

Pertaining to a federated wrapper that is defined to run in the database manager process. See also fenced.

trusted connection

A database connection whose attributes match the attributes of a unique trusted context that is defined at the database server. See also explicit trusted connection, implicit trusted connection.

trusted context

A database security object that enables the establishment of a trusted relationship between a database management system and an external entity.

trusted context default role

The role that is inherited by all users of a trusted context unless it is overridden by a user-specific role in the trusted context definition. See also trusted context user-specific role.

trusted context user

A user ID to which switching the current user ID on a trusted connection is permitted.

trusted context user-specific role

A role that is associated with a specific trusted context user. It overrides the trusted context default role if the current user ID on the trusted connection matches the ID of the specific trusted context user. See also trusted context default role.

trusted relationship

A privileged relationship between two entities such as a middleware server and a database server. This relationship allows for a unique set of interactions between the two entities that would be impossible otherwise.

truststore

A key database that holds signer certificates for only the target servers that the user trusts. See also signer certificate.

tuple

See row.

two-phase commit

A two-step process by which recoverable resources and an external subsystem are committed. During the first step, the database manager subsystems are polled to ensure that they are ready to commit. If all subsystems respond positively, the database manager instructs them to commit. See also distributed transaction.

type-2 index

An index that supports marking an index entry as pseudo deleted.

type annotation

The association of an XML schema type to an XML element node or XML attribute node, usually derived from XML schema validation.

typed parameter marker

A parameter marker that is specified along with its target data type. It has the general form CAST (? AS data type). See also parameter marker, untyped parameter marker.

typed table

A table in which the data type of each column is defined separately or the types for the columns are based on the attributes of a user-defined structured type.

typed view

A view in which the data type of each column is derived from the result table or the types for the columns are based on the attributes of a user-defined structure type.

type promotion

The process of converting an atomic value from an earlier data type to a later data type in an ordered sequence. One example of an ordered sequence is INTEGER, DECIMAL, FLOAT, DOUBLE; another example is anyURI, string. Type promotion can be used, for example, in function calls and in the processing of operators that accept numeric or string operands.

U

UCS-2

Universal Character Set, coded in 2 octets, which means that each character is represented by 16 bits. UCS-2 is a subset of UTF-16. See also UTF-16, UTF-8.

UDDI

See Universal Description, Discovery, and Integration.

UDF

See user-defined function.

uncommitted read (UR)

An isolation level under which a query in a transaction can read any rows, even if there are uncommitted changes to those rows made by statements in other transactions. The UR isolation level is upgraded to CS when data is being modified. See also cursor stability, isolation level, read stability, repeatable read.

unconnected state

A state of a trusted connection in which no user is associated with the connection and no data can be sent or received until the client switches the trusted context user ID.

underlying view

The view on which another view is directly or indirectly defined.

undo

A state of a unit of recovery that indicates that the changes that the unit of recovery made to recoverable DB2 resources must be backed out.
To recover the last edit that has taken place.

unformatted event table

A table that is used to store event monitor data in its original binary format, not in a readable format. See also event monitor.

Unicode

A character encoding standard that supports the interchange, processing, and display of text that is written in the common languages around the world, plus many classical and historical texts. See also multibyte character set.

unidirectional replication

In Q replication, a configuration in which changes that occur in a source table are replicated over WebSphere MQ queues to a target table or are passed to a procedure to manipulate the data. Changes that occur in a target table are not replicated back to a source table.

Uniform Resource Identifier (URI)

A unique address that is used to identify content on the web, such as a page of text, a video or sound clip, a still or animated image, or a program. The most common form of URI is the web page address, which is a particular form or subset of URI called a Uniform Resource Locator (URL). A URI typically describes how to access the resource, the computer that contains the resource, and the name of the resource (a file name) on the computer.

Uniform Resource Locator (URL)

The unique address of an information resource that is accessible in a network such as the Internet. The URL includes the abbreviated name of the protocol used to access the information resource and the information used by the protocol to locate the information resource.

union

An SQL operation that combines the results of two select statements. Unions are often used to merge lists of values that are obtained from several tables.

unique constraint

The rule that no two values in a primary key or key of a unique index can be the same. See also constraint.

unique index

An index that ensures that no identical key values are stored in a column or a set of columns in a table.

unique key

A key that is constrained so that no two of its values are equal. See also constraint, foreign key, primary key.

unit of recovery

A recoverable sequence of operations within a single resource manager, such as an instance of DB2 for z/OS. See also unit of work.

unit of work (UOW)

A recoverable sequence of operations within an application process. At any time, an application process is a single UOW, but the life of an application process can involve many UOWs as a result of commit or rollback operations. In a multisite update operation, a single UOW can include several units of recovery. See also multisite update, remote unit of work, unit of recovery, unit of work.

unit of work boundary

The point in time when a connection disassociates itself from its current transaction. The following events cause a unit of work boundary to be ended: a commit, a rollback, an XA end (success), an XA commit, or an XA rollback.

Universal Description, Discovery, and Integration (UDDI)

A set of standards-based specifications that enables companies and applications to quickly and easily find and use web services over the Internet. See also web service.

unlock

To release an object or system resource that was previously locked and return it to general availability.

untyped expression

A parameter marker or null value that is specified without a target data type. See also untyped parameter marker.

untyped parameter marker

A parameter marker that is specified without its target data type. See also parameter marker, typed parameter marker, untyped expression.

UOW

See unit of work.

updatability

The ability of a cursor to perform positioned updates and deletes. The updatability of a cursor can be influenced by the SELECT statement and the cursor sensitivity option that is specified on the DECLARE CURSOR statement.

updatable result set

A result set that is associated with a cursor that was created with a SELECT statement that contains the FOR UPDATE clause.

update

To apply fixes to a system.

update-anywhere replication

In SQL replication, a type of replication in which all tables are both registered sources and read/write targets. One table is the primary source table for performing a full refresh of all of the others. See also master table, multi-tier replication, peer-to-peer replication, replica table.

update detection

See time-based update detection.

update hole

The location on which a cursor is positioned when a row in the result table is fetched again but values in the underlying tables have been updated such that the row no longer satisfies the search condition. See also delete hole, hole.

update rule

A condition enforced by the database manager that must be met before a column can be updated.

update trigger

A trigger that is activated by an update operation on the table or view that is specified in the trigger definition. See also delete trigger, insert trigger, instead of trigger, trigger.

upgrade

To install a new version or release of a product to replace an earlier version or release of the same product.

UR

See uncommitted read.

URI

See Uniform Resource Identifier.

URL

See Uniform Resource Locator.

usage list

A database object that records each DML statement section that references a particular table or index and captures statistics about how that section affects each object as the section executes.

user copy table

In SQL replication, a replication target table whose content matches all or part of a registered source table and contains only user data columns.

user-defined function (UDF)

A function that is defined to the DB2 database system by using the CREATE FUNCTION statement and that can be referenced thereafter in SQL statements. See also built-in function, external function, function, routine, sourced function, SQL function, table function.

user-defined global variable

A global variable that is defined to the DB2 database system by using the CREATE VARIABLE statement and that can be referenced thereafter in SQL statements. See also built-in global variable, database global variable, global variable.

user-defined procedure

A procedure that is defined to the DB2 database system by using the CREATE PROCEDURE statement and that can be referenced thereafter in SQL statements. See also built-in procedure, external procedure, procedure, routine, SQL procedure.

user exit program

A program, written by a user, that receives control at predefined user exit points. When a user exit program is invoked, the database manager passes control to the executable file. Only one user exit program can be invoked in a database manager instance.

user key

A storage key that can be used by processes when running in user mode (as opposed to kernel node).

user mapping

In a federated system, the association between the authorization ID at the federated server and the authorization ID at the data source. See also user option.

user option

In a federated system, a parameter of the CREATE USER MAPPING or ALTER USER MAPPING statement to which values related to authorization are assigned. See also user mapping.

user table

In SQL replication, a table created for and used by an application before it is defined as a replication source. A user table is used as the source for updates to read-only target tables, consistent-change-data tables, replicas, and row-replica tables.

user temporary table space

A temporary table space that is used to store declared temporary tables. A user temporary table space is not created by default when a database is created. See also temporary table space.

user time

In UNIX, the time spent executing database manager code.

user view

In logical data modeling, a model or representation of critical information that a business requires.

UTC

See Coordinated Universal Time.

UTF-16

Unicode Transformation Format, 16-bit encoding form, which is designed to provide code values for over a million characters and is a superset of UCS-2. The CCSID value for data in UTF-16 format is 1200. See also UCS-2, UTF-8.

UTF-8

Unicode Transformation Format, 8-bit encoding form, which is designed for ease of use with existing ASCII-based systems. The CCSID value for data in UTF-8 format is 1208. See also UCS-2, UTF-16.

V

value

A specific data item at the intersection of a column and row.
The content of a variable, parameter, special register, or field.
The smallest unit of data manipulated in SQL.

variable

A representation of a changeable value. See also global variable.

variable-length string

See varying-length string.

variant function

See non-deterministic function.

varying-length string

A character, graphic, or binary string with a length that is not fixed but that can range within set limits.

vectored I/O

See scattered read.

version

A member of a set of similar programs or packages and, in DB2 for z/OS, similar database request modules (DBRMs) or large objects (LOBs).

version recovery

The restoration of a previous version of a database, using an image that was created during a backup operation. See also crash recovery, rollforward recovery.

view

A logical table that is based on data stored in an underlying set of tables. The data returned by a view is determined by a SELECT statement that is run on the underlying tables. See also base table, table.

Virtual Storage Access Method (VSAM)

An access method for direct or sequential processing of fixed-length and variable-length records on disk devices. The records in a VSAM data set or file can be organized in logical sequence by a key field (key sequence), in the physical sequence in which they are written on the data set or file (entry sequence), or by relative-record number.

visible data partition

A data partition whose data is available to SQL statements. See also attached data partition, detached data partition.

visible scan

A scan whose scan sharing state can be read by other sharing scans. The other scans can use the state information to perform scan throttling and to form scan groups.

volatile table

A table whose cardinality can vary significantly over relatively short periods of time. Compared to statistics that are collected for non-volatile tables, statistics that are collected for volatile tables are less likely to represent the actual data in the tables. The optimizer takes this situation into account when determining access plans involving a volatile table.

Voronoi cell

A region on the surface of the Earth that has boundaries with neighboring regions. The boundaries are defined by the geodesic distances between the center point of the Voronoi cell and the center points of its neighbors. A Voronoi cell consists of all points that are closer to the center of the Voronoi cell than to the center of any other Voronoi cell.

Voronoi cell structure

A subdivision of the surface of the Earth into cells where every point within a particular cell is closer to the center point of that cell than to the center point of any other cell.

VSAM

See Virtual Storage Access Method.

W

wait time: The time interval when a thread or an agent is blocked from using a resource and is not using the processor. See also processing time.
weak dependency: A dependency that causes an object to be rebound when another object that it depends on, such as a table or a data type, is dropped or modified. See also strong dependency.
weakly typed cursor data type: A cursor data type that is not associated with a row data type. A variable or parameter of a weakly typed cursor data type can reference any result set. See also strongly typed cursor data type.
weakly typed distinct type: A distinct type that allows the same operations that would be allowed if the operand data type were the source built-in data type of the weakly typed distinct type. See also distinct type, strongly typed distinct type.
weak typing: A process that enables two objects with mismatched data types to be compared and data to be assigned to an object defined to accept data of a different type. See also implicit casting, strong typing.
web service: An application that performs specific tasks and is accessible through open protocols such as HTTP and SOAP.
WebSphere MQ: A family of IBM licensed programs that provides message queuing services.
well-known address: An address that is used to uniquely identify a particular node in the network to establish connections between nodes. The well-known address is a combination of the network address and the port used on the logical node.
white space: A sequence of one or more characters, such as the blank character, the newline character, or the tab character, that belong to the space character class.
Windows Installer: An installation and configuration service that is used to install DB2 database products on Microsoft Windows operating systems.
WLM application environment: A z/OS Workload Manager attribute that is associated with one or more procedures. The WLM application environment determines the address space in which a given procedure runs.
WLM dispatcher: A CPU resource manager, built into the DB2 engine, that can be used to allocate CPU resources to work that is executing in user and maintenance service classes.
word stemming: A process of linguistic normalization in which the variant forms of a word are reduced to a common form. For example, words such as "connections," "connective," and "connected" are reduced to "connect."
work action: A specific action defined in a work action set to be applied to any activity that falls within the work class with which the work action is associated. See also work action set, work class, work class set.
work action set: A collection of work actions related to a specific work class set. A work action set can be applied to an entire database or an individual service superclass. See also work action, work class, work class set.
work class: A categorization based on the attributes of an activity (for example, its estimated cardinality, estimated cost, or activity type). See also work action, work action set, work class set.
work class set: A grouping of one or more work classes. One or more work action sets can be applied to a single work class set. See also work action, work action set, work class.
work file: In SQL replication, a temporary file that is used by the Apply program when it processes a subscription set.
working directory: The active directory. When a file name is specified without a directory, the current directory is searched.
workload: One or more database activities or requests working within a service class or a database.
workload definition: A set of supplied or user-defined criteria that groups one or more units of work within a database connection into one entity, based on the database connection attributes. This entity can then be assigned to a service class, controlled through thresholds, and monitored. See also service class, threshold.
workload evaluation: The process of determining the workload definition to be used for the current session or connection. This process includes evaluating connection attributes against those of the workload definition and ensuring that the USAGE privilege on the workload definition is held by the current session user. This process is performed at the beginning of the first unit of work (UOW). See also workload re-evaluation.
workload management: The act of monitoring and controlling the flow of work and resource consumption to achieve business objectives while attempting to maximize system efficiency, throughput, or both.
workload occurrence: A specific occurrence of a connection matching a DB2 workload definition for which the current session user has the USAGE privilege.
workload re-evaluation: A repetition of the workload evaluation process that occurs if there is a change in any of the elements used to match a connection to a workload definition. Such elements include a connection attribute, workload definition, or workload authority information for a given unit of work (UOW). See also workload evaluation.
wrapper: In a federated system, the mechanism that the federated server uses for operations such as connecting to a data source and retrieving data from it. To implement a wrapper, the federated server uses routines stored in a library called a wrapper module.
wrapping scan: A scan that starts between the boundaries of the range specified for that scan, continues to the upper boundary, returns to the lower boundary, and continues until it reaches its original starting place. For a table scan, the boundaries are the first and last pages of the table. For a range scan, the boundaries are the first and last pages of the data partition. For an index-driven scan, the boundaries are the start and end keys of the scan range.
write token: The authorization key that is required for updating a file that is referenced in a WRITE PERMISSION ADMIN DATALINK column.
write to operator (WTO): A system service used to send messages to an operator console informing the operator of errors or system conditions that might need correcting. A response is not required.
WTO: See write to operator.

X

XA

A bidirectional interface between one or more resource managers that provide access to shared resources and a transaction manager that monitors and resolves transactions. See also distributed transaction, XA transaction.

XA transaction

In an XA-enabled environment, a unit of work involving one or more resource managers that is coordinated by a transaction manager. See also XA.

XBSA

An industry-standard API set for backup and restore utilities.

XCF

See cross-system coupling facility.

XDA

See XML data area.

XDM

See XQuery and XPath data model.

XDM instance

Data conforming to the XQuery and XPath data model (XDM). See also XML data, XQuery and XPath data model.

XDS

See XML data specifier.

XES

See cross-system extended services.

XID

See exchange station ID.

XML

See Extensible Markup Language.

XML attribute

A name-value pair within a tagged XML element that modifies certain features of the element.

XML collection

A collection of relational tables from which XML documents can be composed or into which XML documents can be decomposed.

XML column

A column of a table that stores XML values and is defined using the SQL built-in data type XML.

XML data

A collection of hierarchical nodes, based on XML instance documents, that can be stored in an XML column or can be returned from an XML column by an SQL or XQuery statement.
Data of type XML, including serialized XML or XDM instances. See also serialized XML, XDM instance.

XML data area (XDA)

See XML storage object.

XML data specifier (XDS)

A string specifying the name, location, and validation schema for a file containing stored XML data. The import, export, and load utilities use an XDS to identify XML-formatted content that must be stored separately from the main data file.

XML document

A well-formed XML artifact that conforms to the XML specification and contains markup tags along with the content, with exactly one root element.

XML element

A logical structure in XML that is delimited by a start tag and an end tag.

XML encoding declaration

The attribute of an XML or TEXT declaration named encoding and its value, which specifies the name of the encoding scheme of XML data.

XML index

See index over XML data.

XML parser

A program that reads XML documents and provides an application with access to their content and structure.

XML parsing

The process of converting a character string or binary string into an XML value. XML parsing is the inverse of serializing.

XML path index

A system-generated index that is associated with an XML column and contains all unique paths that exist in the XML documents that are stored in that XML column. Each XML column in a table has an XML path index.

XML Path Language (XPath)

A language that is designed to uniquely identify or address parts of source XML data, for use with XML-related technologies, such as XSLT, XQuery, and XML parsers. XPath is a World Wide Web Consortium standard.

XML pattern

A slash-separated list of element names that describes a path through an XML document and through specific node characteristics. The pattern selects elements that match the specifications. XML patterns are specified to create indexes on XML columns in a database.

XML publishing function

A function that returns XML values from SQL values.

XML schema

A mechanism for describing and constraining the content of XML files by indicating which elements are allowed and in which combinations. XML schemas are an alternative to document type definitions (DTDs) and can be used to extend functionality in the areas of data typing, inheritance, and presentation.

XML schema document

An XML document with <schema> as the root element that defines the components in one namespace of an XML schema. An XML schema with components in more than one namespace consists of multiple XML schema documents.

XML schema repository (XSR)

A repository that allows the DB2 database system to manage dependencies on externally referenced XML artifacts in XML instance documents within a database. Supported XSR objects include XML schemas, document type definitions (DTDs), and other external entities. When registered with the XSR, these objects have a unique identifier and can be used to validate XML instance documents. See also XSR object.

XML statistics

The statistics that are collected on XML data that is stored in an XML column. The information includes path distribution statistics, which show the frequency of all distinct root-to-node paths. The information also contains path-value distribution statistics, which show the frequency of XML value strings that are truncated to fixed-length prefixes to conserve space.

XML storage object

The object that is used by default to store XML documents contained in XML columns of a table.

XML subtype indicator

An indicator that specifies that a base LOB data type is used to hold XML data.

XML value

See XDM instance.

XPath

See XML Path Language.

XQuery and XPath data model (XDM)

The abstract logical structure that defines all permissible values in the XSLT 2.0, XQuery 1.0, and XPath 2.0 languages. The XDM is described in terms of sequences of atomic values and nodes. See also atomic value, node, sequence, XDM instance.

XQuery constructor

See constructor.

XQuery expression

An expression that operates on instances of the XQuery and XPath data model (XDM) and returns instances of the data model.

XQuery language

An XML query language for interpreting, retrieving, and modifying data as defined by the XQuery and XPath data model, such as XML documents. XQuery Version 1.0 is an extension of XPath Version 2.0.

XRF

See extended recovery facility.

XSL

See Extensible Stylesheet Language.

XSL style sheet

Code that describes how an XML document should be rendered (displayed or printed).

XSLT

See Extensible Stylesheet Language Transformation.

XSR

See XML schema repository.

XSR object

An XML artifact that is registered in the XML schema repository (XSR) and is used to validate XML instance documents. Supported XSR objects include XML schemas, document type definitions (DTDs), and other externally referenced entities. See also XML schema repository.

Z

zigzag join: A join method in which a fact table and two or more dimension tables in a star schema are joined, such that the fact table is accessed using an index. The feedback from the fact table index allows the zigzag join to avoid lookups in the index over the fact table for unproductive dimension key combinations.
z/OS: An IBM mainframe operating system that uses 64-bit real storage. See also Base Control Program.