Terminology mapping: Oracle to IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse
Because Oracle applications can be enabled to work with IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse, it is important to understand how certain Oracle concepts map to IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse concepts.
This section provides an overview of the data management concepts used by Oracle, and the similarities or differences between these concepts and those used by IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse. Table 1 provides a concise summary of commonly used Oracle terms and their IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse equivalents.
| Oracle concept | IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse concept | Notes |
|---|---|---|
| active log | active log | The concepts are the same. |
| actual parameter | argument | The concepts are the same. |
| alert log | db2diag log files and administration notification log | The db2diag log files are primarily intended for use by IBM Software Support for troubleshooting. The administration notification log is primarily intended for use by database and system administrators for troubleshooting. Administration notification log messages are also logged in the db2diag log files, using a standardized message format. |
| archive log | offline archive log | The concepts are the same. |
| archive log mode | log archiving | The concepts are the same. |
| background_dump_dest | diagpath | The concepts are the same. |
| created global temporary table | created global temporary table | The concepts are the same. |
| cursor sharing | statement concentrator | The concepts are the same. |
| data block | data page | The concepts are the same. |
| data buffer cache | buffer pool | The concepts are the same. However, in the IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse product, you can have as many buffer pools as you like, of any page size. |
| data dictionary | system catalog | The system catalog contains metadata in the form of tables and views. The database manager creates
and maintains two sets of system catalog views that are defined on the base system catalog tables:
|
| data dictionary cache | catalog cache | The concepts are the same. |
| data file | container | IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse data is physically stored in containers, which contain objects. |
| database link | nickname | A nickname is an identifier that refers to an object at a remote data source, that is, a federated database object. |
| dual table | dual table | The concepts are the same. |
| dynamic performance views | SQL administrative views | SQL administrative views, which use schema SYSIBMADM, return system data, database configuration, and monitor data about a specific area of the database system. |
| extent | extent | A IBM Db2 on Cloud, IBM Db2 Warehouse on Cloud, and IBM Db2 Warehouse extent is made up of a set of contiguous data pages. |
| formal parameter | parameter | The concepts are the same. |
| global index | nonpartitioned index | The concepts are the same. |
| inactive log | online archive log | The concepts are the same. |
| init.ora file and Server Parameter File (SPFILE) | database manager configuration file and database configuration file | An instance can contain multiple databases. Therefore, configuration parameters and their values are stored at both the instance level, in the database manager configuration file, and at the database level, in the database configuration file. You manage the database manager configuration file through the GET DBM CFG or UPDATE DBM CFG command. You manage the database configuration file through the GET DB CFG or UPDATE DB CFG command. |
| instance | instance or database manager | An instance is a combination of background processes and shared memory. An instance is also known as a database manager. |
| large pool | utility heap | The utility heap is used by the backup, restore, and load utilities. |
| library cache | package cache | The package cache, which is allocated from database shared memory, is used to cache sections for static and dynamic SQL and XQuery statements executed on a database. |
| local index | partitioned index | This is the same concept. |
| materialized view | materialized query table (MQT) | An MQT is a table whose definition is based on the results of a query and can help improve performance. The SQL compiler determines whether a query would run more efficiently against an MQT than it would against the base table on which the MQT is based. |
| noarchive log mode | circular logging | The concepts are the same. |
| Oracle Call Interface (OCI) Oracle Call Interface (OCI) | DB2CI | DB2CI is a C and C++ application programming interface
that uses function calls to connect to Db2 databases, manage
cursors, and perform SQL statements. For more information, see
IBM Data Server Driver for DB2CIfor a list of OCI APIs supported by the Db2CI driver. |
| Oracle Call Interface (OCI) Oracle Call Interface (OCI) | Call Level Interface (CLI) | CLI is a C and C++ application programming interface that uses function calls to pass dynamic SQL statements as function arguments. In most cases, you can replace an OCI function with a CLI function and relevant changes to the supporting program code. |
| ORACLE_SID environment variable | DB2INSTANCE environment variable | The concepts are the same. |
| partitioned tables | partitioned tables | The concepts are the same. |
| Procedural Language/Structured Query Language (PL/SQL) | SQL Procedural Language (SQL PL) | SQL PL is an extension of SQL that consists of statements and other language
elements. SQL PL provides statements for declaring variables and condition handlers, assigning
values to variables, and implementing procedural logic. SQL PL is a subset of the SQL/Persistent
Stored Modules (SQL/PSM) language standard. You can use data server interfaces to compile and execute Oracle PL/SQL statements. |
| program global area (PGA) | application shared memory and agent private memory | Application shared memory stores information that is shared between a database and a particular application: primarily, rows of data that are passed to or from the database. Agent private memory stores information that is used to service a particular application, such as sort heaps, cursor information, and session contexts. |
| redo log | transaction log | The transaction log records database transactions. You can use it for recovery. |
| role | role | The concepts are the same. |
| segment | storage object | The concepts are the same. |
| session | session; database connection | The concepts are the same. |
| startup nomount command | db2start command | The command used to start the instance. |
| synonym | alias | An alias is an alternative name for a table, a view, a nickname, or another alias. The term synonym can be specified instead of alias. Aliases are not used to control what version of a procedure or user-defined function is used by an application. To control the version, use the SET PATH statement to add the required schema to the value of the CURRENT PATH special register. |
| system global area (SGA) | instance shared memory and database shared memory | The instance shared memory stores all of the information for a particular instance, such as lists of all active connections and security information. The database shared memory stores information for a particular database, such as package caches, log buffers, and buffer pools. |
| SYSTEM table space | SYSCATSPACE table space | The SYSCATSPACE table space contains the system catalog. This table space is created by default when you create a database. |
| table space | table space | The concepts are the same. |
| user global area (UGA) | application global memory | Application global memory comprises application shared memory and application-specific memory. |