ALTER FUNCTION statement (compiled SQL scalar function)

Invocation for ALTER FUNCTION (compiled SQL scalar)

This statement can only be dynamically prepared and the DYNAMICRULES run behavior must be specified implicitly or explicitly.

Authorization for ALTER FUNCTION (compiled SQL scalar)

Description for ALTER FUNCTION (compiled SQL scalar)

One of the following three clauses identifies the function to be changed.

FUNCTION function-name

Identifies the SQL function by its function name.

The identified function must be an SQL scalar function. There must be exactly one function with function-name in the schema. The function can have any number of input parameters.¹ If the schema does not contain a function with function-name or contains more than one function with this name, an error occurs.

The function must not be obfuscated.

FUNCTION function-name (parameter-type,...)

Identifies the SQL function by its function signature, which uniquely identifies the function.

function-name

Gives the function name of the SQL function.

If function-name() is specified, the function that is identified must have zero parameters.

(parameter-type,...)

Specifies the number of input parameters of the function and the name and data type of each parameter.

If the function was defined with a table parameter (the LIKE TABLE name AS LOCATOR clause was specified in the CREATE FUNCTION statement to indicate that one of the input parameters is a transition table), the function signature cannot be used to uniquely identify the function. Instead, use one of the other syntax variations to identify the function with its function name, if unique, or its specific name.

(data-type,...)

Identifies the number of input parameters of the function and the data type of each parameter. The data type of each parameter must match the data type that was specified in the CREATE FUNCTION statement for the parameter in the corresponding position. The number of data types and the logical concatenation of the data types are used to uniquely identify the function. Therefore, you cannot change the number of parameters or the data types of the parameters.

For data types that have a length, precision, or scale attribute, you can use a set of empty parentheses, specify a value, or accept the default values:

• Empty parentheses indicate that Db2 is to ignore the attribute when determining whether the data types match.

  For example, DEC() will be considered a match for a parameter of a function defined with a data type of DEC(7,2). Similarly DECFLOAT() will be considered a match for DECFLOAT(16) or DECFLOAT(34).

  FLOAT cannot be specified with empty parentheses because its parameter value indicates different data types (REAL or DOUBLE).

• If you use a specific value for a length, precision, or scale attribute, the value must exactly match the value that was specified (implicitly or explicitly) in the CREATE FUNCTION statement.

  The specific value for FLOAT(n) does not have to exactly match the defined value of the source function because 1<=n<= 21 indicates REAL and 22<=n<=53 indicates DOUBLE. Matching is based on whether the data type is REAL or DOUBLE.

• If length, precision, or scale is not explicitly specified and empty parentheses are not specified, the default length of the data type is implied. The implicit length must exactly match the value that was specified (implicitly or explicitly) in the CREATE FUNCTION statement.

For data types with a subtype or encoding scheme attribute, specifying the FOR subtype DATA clause or the CCSID clause is optional. Omission of either clause indicates that Db2 is to ignore the attribute when determining whether the data types match. If you specify either clause, it must match the value that was implicitly or explicitly specified in the CREATE FUNCTION statement.

See CREATE FUNCTION statement (overview) for more information on the specification of the parameter list.

A function with the function signature must exist in the explicitly or implicitly specified schema.

SPECIFIC FUNCTION specific-name

Identifies a particular user-defined function by its specific name. The name is implicitly or explicitly qualified with a schema name. A compiled SQL scalar function with the specific name must exist in the schema. If the specific name is not qualified, it is implicitly qualified with a schema name as described in the description for FUNCTION function-name.

ACTIVE VERSION, ALL VERSION or, VERSION routine-version-id

Identifies the version of the function that is to be changed.

ACTIVE VERSION

Specifies that the currently active version of the function is to be changed, replaced, or regenerated. If the function is secure, the changed, replaced, or regenerated version remains secure.

ACTIVE VERSION is the default.

ALL VERSIONS

Specifies that all of the versions of the function are to be changed. SECURED and NOT SECURED are the only options that can be changed when ALL VERSIONS is specified.

VERSION routine-version-id

Identifies the version of the function that is to be changed, replaced, or regenerated. routine-version-id is the version identifier that is assigned when the version of the function is defined. routine-version-id must identify a version of the specified function that exists at the current server. If the function is secure, the changed, replaced, or regenerated version remains secure.

ALTER

Specifies that a version of the function is to be changed. When you change a function using ALTER option-list, any option that is not explicitly specified will use the existing value from the version of the function that is being changed.

REPLACE

Specifies that a version of the function is to be replaced.

Binding the replaced version of the function might result in a new access path even if the routine body is not being changed.

When you replace a function, the data types, CCSID specifications, and character data attributes (FOR BIT/SBCS/MIXED DATA) of the parameters must be the same as the attributes of the corresponding parameters for the currently active version of the function. For options that are not explicitly specified, the system default values for those options are used, even if those options were explicitly specified for the version of the function that is being replaced. This is not the case for versions of the function that specified DISABLE DEBUG MODE. If DISABLE DEBUG MODE is specified for a version of a function, it cannot be changed by using the REPLACE clause. When a function definition is replaced, any existing comments in the catalog for that definition of the function are removed.

ADD VERSION routine-version-id

Specifies that a new version of the function is to be created. routine-version-id is the version identifier for the new version of the function. routine-version-id must not identify a version of the specified function that already exists at the current server.

When you add a new version of a function, the data types, CCSID specifications, and character data attributes (FOR BIT/SBCS/MIXED DATA) of the parameters must be the same as the attributes of the corresponding parameters for the currently active version of the function. The parameter names can differ from the other versions of the function. For options that are not explicitly specified, the system default values will be used.

If the function is secure, the new version is considered secure.

ACTIVATE VERSION routine-version-id

Specifies the version of the function that is to be the currently active version. routine-version-id is the version identifier that is assigned when the version of the function is defined. The version that is specified with routine-version-id is the version that will be invoked by a function invocation. routine-version-id must identify a version of the function that exists at the current server.

REGENERATE

Specifies that a version of the function is to be regenerated.

REGENERATE automatically rebinds, at the current server, the package for the SQL control statements for the function and rebinds the package for the SQL statements that are included in the body of the function.

REGENERATE is different than the REBIND PACKAGE command. REBIND PACKAGE rebinds the SQL statements (usually to generate better access paths for those statement) but the SQL control statements in the function definition are not rebound.

When a function definition is regenerated, any existing comments in the catalog for that definition of the function are not removed.

Generally, the REGENERATE keyword is used only for specific situations, such as when implicit regeneration fails for routines or objects, or Db2 maintenance requires objects or routines to be regenerated. For more information, see When to regenerate Db2 database objects and routines.

USING APPLICATION COMPATIBILITY applcompat-level

Specifies the application compatibility level used to regenerate the version of the procedure. The ALTER statement returns an error if the existing definition of the version includes syntax, semantics or options that require a higher application compatibility level. This situation can occur when the version was most recently defined or regenerated while running at a higher application compatibility level than applcompat-level.

The following values can be specified:

VvvRrMmmm

Compatibility with the behavior of the identified Db2 function level. For example, V13R1M506 specifies compatibility with the highest available Db2 13 function level. The equivalent function level or higher must be activated.

For the new capabilities that become available in each application compatibility level, see:

• SQL changes in Db2 13 application compatibility levels
• SQL changes in Db2 12 application compatibility levels

Tip: Extra program preparation steps might be required to increase the application compatibility level for applications that use data server clients or drivers to access Db2 for z/OS®. For more information, see Setting application compatibility levels for data server clients and drivers.

V12R1

Compatibility with the behavior of Db2 12 function level 500. This value has the same result as specifying V12R1M500.

V11R1

Compatibility with the behavior of Db2 11 new-function mode.

V10R1

Compatibility with the behavior of DB2® 10 new-function mode. For more information, see V10R1 application compatibility level.

If USING APPLICATION COMPATIBILITY is omitted, the regeneration uses the APPLCOMPAT value of the applicable SYSIBM.SYSPACKAGE catalog table row.

DROP VERSION routine-version-id

Drops the version of the function that is identified with routine-version-id. routine-version-id is the version identifier that is assigned when the version is defined. routine-version-id must identify a version of the function that exists at the current server and must not identify the currently active version of the function. Only the identified version of the function is dropped.

When only a single version of the function exists at the current server, use the DROP FUNCTION statement to drop the function.

RETURNS

Identifies the output of the function.

data-type2

Specifies the data type of the output. The data type must match the data type that was specified in the RETURNS clause of the CREATE FUNCTION statement.

NOT DETERMINISTIC or DETERMINISTIC

Specifies whether the function returns the same results each time that the function is invoked with the same input arguments.

NOT DETERMINISTIC

The function might not return the same result each time that the function is invoked with the same input arguments. The function depends on some state values that affect the results. Db2 uses this information to disable the merging of views and table expressions when processing SELECT or SQL data change statements that refer to this function. An example of a function that is not deterministic is one that generates random numbers.

NOT DETERMINISTIC must be specified explicitly or implicitly if the function program accesses a special register or invokes another function that is not deterministic.

DETERMINISTIC

The function always returns the same result each time that the function is invoked with the same input arguments. An example of a deterministic function is a function that calculates the square root of the input. Db2 uses this information to enable the merging of views and table expressions for SELECT or SQL data change statements that refer to this function. If applicable, specify DETERMINISTIC to prevent non-optimal access paths from being chosen for SQL statements that refer to this function.

Db2 does not verify that the function program is consistent with the specification of DETERMINISTIC or NOT DETERMINISTIC.

EXTERNAL ACTION or NO EXTERNAL ACTION

Specifies whether the function takes an action that changes the state of an object that Db2 does not manage. An example of an external action is sending a message or writing a record to a file.

EXTERNAL ACTION

The function can take an action that changes the state of an object that Db2 does not manage.

Some SQL statements that invoke functions with external actions can result in incorrect results if parallel tasks execute the function. For example, if the function sends a note for each initial call to it, one note is sent for each parallel task instead of once for the function.

If you specify EXTERNAL ACTION, Db2:

• Materializes the views and table expressions in SELECT or SQL data change statements that refer to the function. This materialization can adversely affect the access paths that are chosen for the SQL statements that refer to this function. Do not specify EXTERNAL ACTION if the function does not have an external action.
• Does not move the function from one task control block (TCB) to another between FETCH operations.
• Does not allow another function or stored procedure to use the TCB until the cursor is closed. This is also applicable for cursors declared WITH HOLD.

The only changes to resources made outside of Db2 that are under the control of commit and rollback operations are those changes made under RRS control.

EXTERNAL ACTION must be specified implicitly or explicitly specified if the SQL routine body invokes a function that is defined with EXTERNAL ACTION.

NO EXTERNAL ACTION

The function does not take any action that changes the state of an object that Db2 does not manage. Db2 uses this information to enable the merging of views and table expressions for SELECT or SQL data change statements that refer to this function. If applicable, specify NO EXTERNAL ACTION to prevent non-optimal access paths from being chosen for SQL statements that refer to this function.

Db2 does not verify that the function program is consistent with the specification of EXTERNAL ACTION or NO EXTERNAL ACTION.

MODIFIES SQL DATA, READS SQL DATA, or CONTAINS SQL

Specifies the classification of SQL statements and nested routines that this routine can execute or invoke. The database manager verifies that the SQL statements issued by the function, and all routines locally invoked by the routine, are consistent with this specification; the verification is not performed when nested remote routines are invoked. For the classification of each statement, see SQL statement data access classification for routines.

MODIFIES SQL DATA

Specifies that the function can execute any SQL statement except the statements that are not supported in functions. Do not specify MODIFIES SQL DATA when ALLOW PARALLEL is in effect.

If a function that is defined with MODIFIES SQL DATA is invoked anywhere except the select-clause of the outermost SELECT statement, the results are unpredictable because the function can be invoked multiple times depending on the access plan that is used.

Recommendation: If a SELECT statement invokes a function that is defined with the MODIFIES SQL DATA option, ensure that statements nested inside the function do not modify objects that are referenced in any SQL statement at a higher level of nesting. Otherwise, unpredictable results are likely to occur.

READS SQL DATA

Specifies that the function can execute statements with a data access classification of READS SQL DATA, CONTAINS SQL, or NO SQL. The function cannot execute SQL statements that modify data.

READS SQL DATA is the default.

CONTAINS SQL

Specifies that the function can execute only SQL statements with a data access classification of CONTAINS SQL or NO SQL. The function cannot execute SQL statements the read or modify data.

CALLED ON NULL INPUT or RETURNS NULL ON NULL INPUT

Specifies whether the function is invoked if any of the input arguments is null at execution time.

CALLED ON NULL INPUT

Specifies that the function is to be invoked, if any, or all, argument values are null. This specification means that the body of the function must be coded to test for null argument values.

CALLED ON NULL INPUT is the default.

RETURNS NULL ON NULL INPUT

Specifies that the function is not invoked and returns the null value if any of the input arguments is null.

STATIC DISPATCH

At function resolution time, Db2 chooses a function based on the static (or declared) types of the function parameters.

STATIC DISPATCH is the default.

ALLOW PARALLEL or DISALLOW PARALLEL

Specifies if the function can be run in parallel. The default is DISALLOW PARALLEL, if you specify one or more of the following clauses:

• NOT DETERMINISTIC
• EXTERNAL ACTION
• MODIFIES SQL DATA

Otherwise, ALLOW PARALLEL is the default.

ALLOW PARALLEL

Specifies that the function can be run in parallel.

DISALLOW PARALLEL

Specifies that the function cannot be run in parallel.

ALLOW DEBUG MODE, DISALLOW DEBUG MODE, or DISABLE DEBUG MODE

Specifies whether this version of the routine can be run in debugging mode. The default is determined using the value of the CURRENT DEBUG MODE special register.

ALLOW DEBUG MODE

Specifies that this version of the routine can be run in debugging mode. When this version of the routine is invoked and debugging is attempted, a WLM environment must be available.

DISALLOW DEBUG MODE

Specifies that this version of the routine cannot be run in debugging mode.

You can use an ALTER statement to change this option to ALLOW DEBUG MODE for this initial version of the routine.

DISABLE DEBUG MODE

Specifies that this version of the routine can never be run in debugging mode.

This version of the routine cannot be changed to specify ALLOW DEBUG MODE or DISALLOW DEBUG MODE after this version of the routine has been created or altered to use DISABLE DEBUG MODE. To change this option, drop the routine and create it again using the option that you want. An alternative to dropping and recreating the routine is to create a version of the routine that uses the option that you want and making that version the active version.

When DISABLE DEBUG MODE is in effect, the WLM ENVIRONMENT FOR DEBUG MODE is ignored.

QUALIFIER schema-name

Specifies the implicit qualifier that is used for unqualified object names that are referenced in the procedure body. For information about how the default for this option is determined, see Unqualified alias, index, JAR file, mask, permission, sequence, table, trigger, and view names.

PACKAGE OWNER authorization-name

FL 500

Specifies the owner of the package that is associated with the version of the routine. The default is that the authorization-name is a role if the process is running in a trusted context defined with the role as object owner and qualifier attributes. Otherwise, the default is the SQL authorization ID of the process.

AS ROLE

Specifies that authorization-name is a role that exists at the current server.

AS USER

Specifies that authorization-name is an authorization ID.

ASUTIME

Specifies the total amount of processor time, in CPU service units, that a single invocation of a routine can run. The value is unrelated to the ASUTIME column of the resource limit specification table.

When you are debugging a routine, setting a limit can be helpful in case the routine gets caught in a loop. For information on service units, see z/OS MVS Initialization and Tuning Guide.

NO LIMIT

Specifies that there is no limit on the service units.

NO LIMIT is the default.

LIMIT integer

The limit on the number of CPU service units is a positive integer in the range 1–2 147 483 647. If the procedure uses more service units than the specified value, Db2 cancels the procedure. The CPU cycles that are consumed by parallel tasks in a procedure do not contribute towards the specified ASUTIME LIMIT.

INHERIT SPECIAL REGISTERS or DEFAULT SPECIAL REGISTERS

Specifies how special registers are set on entry to the routine.

INHERIT SPECIAL REGISTERS

Specifies that the values of special registers are inherited, according to the rules that are listed in the table for characteristics of special registers in a routine in Table 1.

INHERIT SPECIAL REGISTERS is the default.

DEFAULT SPECIAL REGISTERS

Specifies that special registers are initialized to the default values, as indicated by the rules in the table for characteristics of special registers in a routine in Table 1.

WLM ENVIRONMENT FOR DEBUG MODE name

Specifies the WLM (workload manager) application environment that is used by Db2 when debugging the routine. The name of the WLM environment is an SQL identifier.

If you do not specify WLM ENVIRONMENT FOR DEBUG MODE, Db2 uses the default WLM-established stored procedure address space specified at installation time.

You must have the appropriate authority for the WLM application environment.

The WLM ENVIRONMENT FOR DEBUG MODE value is ignored when DISABLE DEBUG MODE is in effect.

CURRENT DATA YES or CURRENT DATA NO

Specifies whether to require data currency for read-only and ambiguous cursors when the isolation level of cursor stability is in effect. CURRENT DATA also determines whether block fetch can be used for distributed, ambiguous cursors.

CURRENT DATA YES

Specifies that data currency is required for read-only and ambiguous cursors. Db2 acquired page or row locks to ensure data currency. Block fetch is ignored for distributed, ambiguous cursors.

CURRENT DATA NO

Specifies that data currency is not required for read-only and ambiguous cursors. Block fetch is allowed for distributed, ambiguous cursors. Use of CURRENT DATA NO is not recommended if the routine attempts to dynamically prepare and execute a DELETE WHERE CURRENT OF statement against an ambiguous cursor after that cursor is opened. You receive a negative SQLCODE if your routine attempts to use a DELETE WHERE CURRENT OF statement for any of the following cursors:

• A cursor that is using block fetch
• A cursor that is using query parallelism
• A cursor that is positioned on a row that is modified by this or another application process

CURRENT DATA NO is the default.

DEGREE

Specifies whether to attempt to run a query using parallel processing to maximize performance.

1

Specifies that parallel processing should not be used.

1 is the default.

ANY

Specifies that parallel processing can be used.

CONCURRENT ACCESS RESOLUTION

Specifies the whether processing uses only committed data or whether it will wait for commit or rollback of data that is in the process of being updated.

WAIT FOR OUTCOME

Specifies that processing will wait for the commit or rollback of data that is in the process of being updated.

USE CURRENTLY COMMITTED

Specifies that processing use the currently committed version of the data when data that is in the process of being updated is encountered. USE CURRENTLY COMMITTED is applicable on scans that access tables that are defined in universal table spaces with row or page level lock size.

When there is lock contention between a read transaction and an insert transaction, USE CURRENTLY COMMITTED is applicable to scans with isolation level CS or RS. Applicable scans include intent read scans for read-only and ambiguous queries and for updatable cursors. USE CURRENTLY COMMITTED is also applicable to scans initiated from WHERE predicates of UPDATE or DELETE statements and the subselect of INSERT statements.

When there is lock contention is between a read transaction and a delete transaction, USE CURRENTLY COMMITTED is applicable to scans with isolation level CS and when CURRENT DATA NO is specified.

DYNAMICRULES

Specifies the values that apply, at run time, for the following dynamic SQL attributes:

• The authorization ID that is used to check authorization
• The qualifier that is used for unqualified objects
• The source for application programming options that Db2 uses to parse and semantically verify dynamic SQL statements

DYNAMICRULES also specifies whether dynamic SQL statements can include GRANT, REVOKE, ALTER, CREATE, DROP, and RENAME statements.

In addition to the value of the DYNAMICRULES clause, the run time environment of a routine controls how dynamic SQL statements behave at run time. The combination of the DYNAMICRULES value and the run time environment determines the value for the dynamic SQL attributes. That set of attribute values is called the dynamic SQL statement behavior. The following values can be specified:

RUN

Specifies that dynamic SQL statements are to be processed using run behavior.

RUN is the default.

BIND

Specifies that dynamic SQL statements are to be processed using bind behavior.

DEFINEBIND

Specifies that dynamic SQL statements are to be processed using either define behavior or bind behavior.

DEFINERUN

Specifies that dynamic SQL statements are to be processed using either define behavior or run behavior.

INVOKEBIND

Specifies that dynamic SQL statements are to be processed using either invoke behavior or bind behavior.

INVOKERUN

Specifies that dynamic SQL statements are to be processed using either invoke behavior or run behavior.

See For information on the effects of these options, see Authorization IDs and dynamic SQL.

APPLICATION ENCODING SCHEME

Specifies the default encoding scheme for SQL variables in static SQL statements in the routine body. The value is used for defining an SQL variable in a compound statement if the CCSID clause is not specified as part of the data type, and the PARAMETER CCSID routine option is not specified.

ASCII

Specifies that the data is encoded using the ASCII CCSIDs of the server.

EBCDIC

Specifies that the data is encoded using the EBCDIC CCSIDs of the server.

UNICODE

Specifies that the data is encoded using the Unicode CCSIDs of the server.

See the ENCODING bind option in ENCODING bind option for information about how the default for this option is determined.

WITH EXPLAIN or WITHOUT EXPLAIN

Specifies whether information will be provided about how SQL statements in the routine will execute.

WITHOUT EXPLAIN

Specifies that information will not be provided about how SQL statements in the routine will execute.

You can get EXPLAIN output for a statement that is embedded in a routine that is specified using WITHOUT EXPLAIN by embedding the SQL statement EXPLAIN in the routine body. Otherwise, the value of the EXPLAIN option applies to all explainable SQL statements in the routine body, and to the fullselect portion of any DECLARE CURSOR statements.

WITHOUT EXPLAIN is the default.

WITH EXPLAIN

Specifies that information will be provided about how SQL statements in the routine will execute. Information is inserted into the table owner.PLAN_TABLE. owner is the authorization ID of the owner of the routine. Alternatively, the authorization ID of the owner of the routine can have an alias as owner.PLAN_TABLE that points to the base table, PLAN_TABLE. owner must also have the appropriate SELECT and INSERT privileges on that table. WITH EXPLAIN does not obtain information for statements that access remote objects. PLAN_TABLE must have a base table and can have multiple aliases with the same table name, PLAN_TABLE, but have different schema qualifiers. It cannot be a view or a synonym and should exist before the CREATE statement is processed. In all inserts to owner.PLAN_TABLE, the value of QUERYNO is the statement number that is assigned by Db2.

The WITH EXPLAIN option also populates two optional tables, if they exist: DSN_STATEMNT_TABLE and DSN_FUNCTION_TABLE. DSN_STATEMNT_TABLE contains an estimate of the processing cost for an SQL statement and DSN_FUNCTION_TABLE contains information about function resolution. For more information, see EXPLAIN tables.

For more information about the EXPLAIN statement, including a description of the tables that are populated by the WITH EXPLAIN option, see EXPLAIN statement.

WITH IMMEDIATE WRITE or WITHOUT IMMEDIATE WRITE

Specifies whether immediate writes are to be done for updates that are made to group buffer pool dependent page sets or partitions. This option is only applicable for data sharing environments. The IMMEDWRITE subsystem parameter has no affect of this option. IMMEDWRITE bind option shows the implied hierarchy of the IMMEDWRITE bind option (which is similar to this routine option) as it affects run time.

WITHOUT IMMEDIATE WRITE

Specifies that normal write activity is performed. Updated pages that are group buffer pool dependent are written at or before phase one of commit or at the end of abort for transactions that have been rolled back.

WITHOUT IMMEDIATE WRITE is the default.

WITH IMMEDIATE WRITE

Specifies that updated pages that are group buffer pool dependent are immediately written as soon as the buffer update completes. Updated pages are written immediately even if the buffer is updated during forward progress or during the rollback of a transaction. WITH IMMEDIATE WRITE might impact performance.

ISOLATION LEVEL RR, RS, CS, or UR

Specifies how far to isolate the routine from the effects of other running applications. For information about isolation levels, see Choosing an ISOLATION option.

RR

Specifies repeatable read.

RS

Specifies read stability.

CS

Specifies cursor stability. CS is the default.

UR

Specifies uncommitted read.

OPTHINT 'hint-id'

Specifies whether query optimization hints are used for static SQL statements that are contained within the body of the routine.

hint-id is a character string of up to 128 bytes in length, which is used by the Db2 subsystem when searching the PLAN_TABLE for rows to use as input. The default value is an empty string (''), which indicates that the Db2 subsystem does not use optimization hints for static SQL statements.

Optimization hints are only used if optimization hints are enabled for your system. For more information, see OPTIMIZATION HINTS field (OPTHINTS subsystem parameter).

SQL PATH

Specifies the SQL path that the Db2 subsystem uses to resolve unqualified user-defined types, functions, and procedure names (in CALL statements) in the body of the routine. The default value is "SYSIBM", "SYSFUN", "SYSPROC", "SYSIBMADM", and the value of the QUALIFIER option, which is the qualifier for the trigger that is the target of the statement. The maximum length of the SQL path is 2048 bytes. Db2 calculates the length by taking each schema-name that is specified and removing any trailing blanks from it, adding two delimiters around it, and adding one comma after each schema name except for the last name. The length of the resulting string cannot exceed 2048 bytes.

schema-name

Identifies a schema. Db2 does not verify that the schema exists when the ALTER statement is processed. The same schema name should not appear more than one time in the list of schema names.

SYSPUBLIC must not be specified for the SQL path.

SYSTEM PATH

Specifies the schema names "SYSIBM", "SYSFUN", "SYSPROC", "SYSIBMADM".

SESSION_USER or USER

Specifies the value of the SESSION_USER (or USER) special register. At the time the ALTER statement is processed, the actual length is included in the total length of the list of schema names that is specified for the SQL PATH option.

REOPT

Specifies if Db2 will determine the access path at run time by using the values of SQL variables or SQL parameters, parameter markers, and special registers.

NONE

Specifies that Db2 does not determine the access path at run time by using the values of SQL variables or SQL parameters, parameter markers, and special registers.

NONE is the default.

ALWAYS

Specifies that Db2 always determines the access path at run time each time an SQL statement is run. Do not specify REOPT ALWAYS with the WITH KEEP DYNAMIC or NODEFER PREPARE clauses.

ONCE

Specifies that Db2 determine the access path for any dynamic SQL statements only once, at the first time the statement is opened. This access path is used until the prepared statement is invalidated or removed from the dynamic statement cache and need to be prepared again.

QUERY ACCELERATION

Specifies whether a static SQL query is bound for acceleration, and if so, with what behavior.

NONE

Specifies that no static SQL query in the application is bound for acceleration or will be accelerated when the application is run.

ENABLE

Specifies that a static SQL query is bound for acceleration if it satisfies the acceleration criteria, including the cost and heuristics criteria. The query is routed to an accelerator when the application runs. Otherwise, if the static query does not satisfy the acceleration criteria, the query is bound for execution in Db2.

If an error condition, such as one of the following examples, occurs while executing the accelerated static query when the application is run, Db2 fails the static query and returns a negative SQL code to the application:

• A failure occurs while running the static query on the accelerator.
• The accelerator returns an error for the query.
• The accelerator is not started and Db2 cannot route the static query to the accelerator for execution.

ENABLE WITH FAILBACK

Results in the same behavior as ENABLE, except if one of the error conditions occurs on the first OPEN of the accelerated static query when the application is run. In this case, instead of failing the static query and returning a negative SQL code to the application, Db2 performs a temporary statement-level incremental bind of the query and runs the query in Db2. The application does not see the acceleration failure. Failback to Db2 is not possible after the application does a successful OPEN for the query on the accelerator.

ELIGIBLE

Specifies that a static SQL query is bound for acceleration if the query meets the basic acceleration criteria, regardless of the cost or heuristics criteria. The query is routed to the accelerator when the application runs.

Like the behavior for ENABLE, if an error condition occurs while executing the accelerated static query when the application is run, Db2 fails the static query and returns a negative SQL code to the application.

ALL

Specifies that all of the static SQL queries in the application are to be bound for acceleration and routed to the accelerator when the application runs. If Db2 determines that a static query cannot be bound to run on the accelerator and the query references a user base table or view, the BIND or REBIND PACKAGE operation fails with an error message for that query. (A failure exception is made for declared global temporary tables (DGTTs) and created global temporary tables and (CGTTs) because these tables cannot be accelerated.)

Like the behavior for ENABLE, if an error condition occurs while executing the accelerated static query when the application is run, Db2 fails the static query and returns a negative SQL code to the application.

This bind option does not apply to a fullselect or WITH common-table-expression that is specified in a RETURN statement for the routine, or in a SET host-variable-assignment that is used in the routine. The queries that are specified in these cases cannot be accelerated.

GET_ACCEL_ARCHIVE

Specifies whether a static SQL query that is bound for acceleration retrieves archived data on the accelerator, instead of active data.

NO

Specifies that no static SQL query is bound to retrieve archived data from the accelerator. If the static query also is not bound for acceleration, the query is bound to run in Db2.

If the static query is bound for acceleration because the QUERYACCELERATION bind option was specified, the query is routed to the accelerator when the application runs; however, the query does not retrieve any archived data.

YES

Specifies that if all of the following criteria are met, the query is bound for acceleration and retrieves the archived data on the accelerator when the application runs:

• The QUERYACCELERATION bind option is also specified.
• The static SQL query references an accelerated table that has partitioned data archived on an accelerator.
• The static query satisfies the acceleration criteria that is specified by the QUERYACCELERATION bind option.

If the static query does not satisfy the acceleration criteria that is specified by the QUERYACCELERATION bind option, the BIND or REBIND PACKAGE operation fails with an error message for that query.

This bind option does not apply to a fullselect or WITH common-table-expression that is specified in a RETURN statement for the routine, or in a SET host-variable-assignment that is used in the routine. The queries that are specified in these cases cannot be accelerated.

ACCELERATION WAITFORDATA

Specifies the maximum amount of time, if any, that an accelerator will delay a query while the accelerator waits for the replication of committed Db2 data changes that occurred prior to Db2 running the query.

For static accelerated queries, you must also set the QUERYACCELERATION bind option for this function or procedure to a valid value other than NONE to request that static queries be accelerated. If the QUERYACCELERATION bind option value is set to NONE, the ACCELERATIONWAITFORDATA bind option is accepted and the package is bound with the option value; however, the option will not apply to static SQL queries because no static queries will be accelerated.

For dynamic accelerated queries, specifying the ACCELERATION WAITFORDATA bind option also initializes the CURRENT QUERY ACCELERATION WAITFORDATA special register, which is used for the dynamic queries in the Db2 function or procedure if the function or procedure option DEFAULT SPECIAL REGISTERS is also used. Initializing CURRENT QUERY ACCELERATION WAITFORDATA to a value greater than 0 specifies that Db2 and the accelerator will apply WAITFORDATA delay behavior and restrictions to all dynamic SQL queries to be accelerated from the Db2 function or procedure. The CURRENT QUERY ACCELERATION special register must also have a valid value other than NONE to request that dynamic queries be accelerated.

nnnn.m

Specifies a DECIMAL(5,1) numeric-constant value that specifies the maximum number of seconds that the accelerator will delay a query while the accelerator waits for the replication of committed Db2 data changes that occurred prior to Db2 running the query.

You can specify a value in the range of 0.0–3600.0 seconds. For example, a value of 20.0 represents 20.0 seconds (or 20000 milliseconds), and a value of 30.5 represents 30.5 seconds (or 30500 milliseconds). The maximum value of 3600.0 means they the query is delayed for 3600 seconds.

You can also specify the value as an INTEGER numeric-constant value ranging 0–3600 seconds, which Db2 will convert to a DECIMAL(5,1) value.

Important: When a non-zero value is specified for the ACCELERATIONWAITFORDATA bind option, Db2 and the accelerator will apply other WAITFORDATA delay behaviors, restrictions, and requirements to all queries that will be accelerated from the application package. These behaviors, restrictions, and requirements can cause queries that were formerly accelerated successfully to no longer be accelerated or to fail. See SET CURRENT QUERY ACCELERATION WAITFORDATA statement for more information about WAITFORDATA behaviors, restrictions, and requirements.

ACCELERATOR

Specifies an accelerator server that, if enabled and available, Db2 will consider as the preferred accelerator for eligible SQL queries before sending the queries to other accelerator servers. If the specified accelerator server is not enabled or available, Db2 will send the queries to other available accelerator servers.

VALIDATE RUN or VALIDATE BIND

Specifies whether to recheck, at run time, errors of the type "OBJECT NOT FOUND" and "NOT AUTHORIZED" that are found during bind or rebind. The option has no effect if all objects and needed privileges exist.

VALIDATE RUN

Specifies that if needed objects or privileges do not exist when the CREATE statement is processed, warning messages are returned, but the CREATE statement succeeds. The Db2 subsystem rechecks for the objects and privileges at run time for those SQL statements that failed the checks during processing of the CREATE statement. The authorization checks the use of the authorization ID of the owner of the routine.

VALIDATE RUN is the default.

VALIDATE BIND

Specifies that if needed objects or privileges do not exist at the time the CREATE statement is processed, an error is issued and the CREATE statement fails.

ROUNDING

Specifies the rounding mode for manipulation of DECFLOAT data. The default value is taken from the DEFAULT DECIMAL FLOATING POINT ROUNDING MODE in DECP.

DEC_ROUND_CEILING

Specifies numbers are rounded towards positive infinity.

DEC_ROUND_DOWN

Specifies numbers are rounded towards 0 (truncation).

DEC_ROUND_FLOOR

Specifies numbers are rounded towards negative infinity.

DEC_ROUND_HALF_DOWN

Specifies numbers are rounded to nearest; if equidistant, round down.

DEC_ROUND_HALF_EVEN

Specifies numbers are rounded to nearest; if equidistant, round so that the final digit is even.

DEC_ROUND_HALF_UP

Specifies numbers are rounded to nearest; if equidistant, round up.

DEC_ROUND_UP

Specifies numbers are rounded away from 0.

DATE FORMAT ISO, EUR, USA, JIS, or LOCAL

Specifies the date format for result values that are string representations of date or time values. For more information, see String representations of datetime values.

The default format is specified in the DATE FORMAT field of installation panel DSNTIP4 of the system where the routine is defined. You cannot use the LOCAL option unless you have a date exit routine.

DECIMAL(15), DECIMAL(31), DECIMAL(15,s), or DECIMAL(31,s)

Specifies the maximum precision that is to be used for decimal arithmetic operations. For more information see Arithmetic with two decimal operands. The default format is specified in the DECIMAL ARITHMETIC field of installation panel DSNTIPF of the system where the routine is defined. If the form pp.s is specified, s must be a number in the range 1–9. s represents the minimum scale that is to be used for division.

FOR UPDATE CLAUSE OPTIONAL or FOR UPDATE CLAUSE REQUIRED

Specifies whether the FOR UPDATE clause is required for a DECLARE CURSOR statement if the cursor is to be used to perform positioned updates.

FOR UPDATE CLAUSE REQUIRED

Specifies that a FOR UPDATE clause must be specified as part of the cursor definition if the cursor will be used to make positioned updates.

FOR UPDATE CLAUSE REQUIRED is the default.

FOR UPDATE CLAUSE OPTIONAL

Specifies that the FOR UPDATE clause does not need to be specified in order for a cursor to be used for positioned updates. The routine body can include positioned UPDATE statements that update columns that the user is authorized to update.

The FOR UPDATE clause with no column list applies to static or dynamic SQL statements. Even if you do not use this clause, you can specify FOR UPDATE OF with a column list to restrict updates to only the columns that are identified in the FOR UPDATE clause and to specify the acquisition of update locks.

TIME FORMAT ISO, EUR, USA, JIS, or LOCAL

Specifies the time format for result values that are string representations of date or time values. For more information, see String representations of datetime values.

The default format is specified in the TIME FORMAT field of installation panel DSNTIP4 of the system where the routine is defined. You cannot use the LOCAL option unless you have a date exit routine.

SECURED or NOT SECURED

Specifies if the function is considered secure. When the option is specified with the ALL VERSIONS clause, it applies to all existing versions and to any future versions of the function. When it is specified with other clauses such as ADD VERSION, or REPLACE, the value must be the same as the value that is in effect for the function that is being changed.

SECURED

Specifies that the function is considered secure.

Use of this clause or keyword might invalidate packages that depend on the target object, or packages that depend on related objects through cascading effects. See Changes that invalidate packages.

NOT SECURED

Specifies that the function is considered not secure. NOT SECURED must not be specified when a row permission or a column mask depends on the function.

When the function is invoked, the arguments of the function must not reference a column for which a column mask is enabled when the table is using active column access control.

Use of this clause or keyword might invalidate packages that depend on the target object, or packages that depend on related objects through cascading effects. See Changes that invalidate packages.

BUSINESS_TIME SENSITIVE

Determines whether references to application-period temporal tables in both static and dynamic SQL statements are affected by the value of the CURRENT TEMPORAL BUSINESS_TIME special register.

YES

References to application-period temporal tables are affected by the value of the CURRENT TEMPORAL BUSINESS_TIME special register. YES is the default value.

NO

References to application-period temporal tables are not affected by the value of the CURRENT TEMPORAL BUSINESS_TIME special register.

For more information, see CURRENT TEMPORAL BUSINESS_TIME special register.

SYSTEM_TIME SENSITIVE

Determines whether references to system-period temporal tables in both static and dynamic SQL statements are affected by the value of the CURRENT TEMPORAL SYSTEM_TIME special register.

YES

References to system-period temporal tables are affected by the value of the CURRENT TEMPORAL SYSTEM_TIME special register. YES is the default value.

NO

References to system-period temporal tables are not affected by the value of the CURRENT TEMPORAL SYSTEM_TIME special register.

For more information, see CURRENT TEMPORAL SYSTEM_TIME special register.

ARCHIVE SENSITIVE

Determines whether references to archive-enabled tables in SQL statements are affected by the value of the SYSIBMADM.GET_ARCHIVE built-in global variable.

YES

References to archive-enabled tables are affected by the value of the SYSIBMADM.GET_ARCHIVE built-in global variable. YES is the default value.

NO

References to archive-enabled tables are not affected by the value of the SYSIBMADM.GET_ARCHIVE built-in global variable. For more information, see GET_ARCHIVE built-in global variable.

APPLCOMPAT applcompat-level

Specifies the application compatibility level behavior for static SQL statements in the function body. If this option is not specified then the behavior is determined, in priority order, by the applcompat-level of the previous bind of the package if one exists, or the APPLCOMPAT subsystem parameter.

The following applcompat-level values can be specified:

VvvRrMmmm

Compatibility with the behavior of the identified Db2 function level. For example, V13R1M506 specifies compatibility with the highest available Db2 13 function level. The equivalent function level or higher must be activated.

For the new capabilities that become available in each application compatibility level, see:

• SQL changes in Db2 13 application compatibility levels
• SQL changes in Db2 12 application compatibility levels

Tip: Extra program preparation steps might be required to increase the application compatibility level for applications that use data server clients or drivers to access Db2 for z/OS. For more information, see Setting application compatibility levels for data server clients and drivers.

V12R1

Compatibility with the behavior of Db2 12 function level 500. This value has the same result as specifying V12R1M500.

V11R1

Compatibility with the behavior of Db2 11 new-function mode.

V10R1

Compatibility with the behavior of DB2 10 new-function mode. For more information, see V10R1 application compatibility level.

CONCENTRATE STATEMENTS OFF or CONCENTRATE STATEMENTS WITH LITERALS

Specifies whether each dynamic SQL statement in the routine that specifies literal constants will be cached as a separate unique statement entry in the dynamic statement cache, instead of sharing an existing statement in the cache. Dynamic SQL statements are eligible to share an existing statement in the cache if the new statement meets all of the conditions for sharing a cached version of the same dynamic statement, except that the new statement specifies one or more literal constants that are different than the cached statement.

CONCENTRATE STATEMENTS OFF

Specifies that each dynamic SQL statement that specifies literal constants will be cached as a unique statement entry if it specifies one or more constants that are different than the cached version of the same dynamic statement. CONCENTRATE STATEMENTS OFF is the default dynamic statement caching behavior.

CONCENTRATE STATEMENTS WITH LITERALS

Specifies that each dynamic SQL statement that specifies literal constants will share a cached version of the same dynamic statement that is also prepared using the CONCENTRATE STATEMENTS WITH LITERALS option, if the new dynamic statement meets all of the conditions for sharing the cached statement, and the constants that are specified can be reused in place of the constants in the cached statement.

SQL-routine-body

Specifies a single SQL control statement, including a compound-statement. See SQL procedural language (SQL PL) for more information about defining SQL functions.

A call to a procedure that issues a COMMIT, ROLLBACK, CONNECT, RELEASE, or SET CONNECTION statement is not allowed in a function.

If the SQL-routine-body is a compound statement, it must contain at least one RETURN statement and a RETURN statement must be executed when the function is invoked.

An ALTER FUNCTION (compiled SQL scalar) statement or an ALTER PROCEDURE (SQL native) statement with an ADD VERSION or REPLACE clause is not allowed in an SQL-routine-body.

Notes for ALTER FUNCTION (compiled SQL scalar)

The order of options and the RETURNS clause

The RETURNS clause must precede the options-list. If the body of the function contains only a RETURN-statement, RETURN-statement must be specified after the RETURNS clause and the options-list in the routine body.

ALTER FUNCTION for in use functions:

ALTER FUNCTION will be locked out from making changes if the function is in use. For example, if a query that is currently running is referencing an SQL scalar function named 'fn1' (routine-version-id is 'v1'), an ALTER FUNCTION fn1 ACTIVATE VERSION v2 statement will wait for the query that is currently running to complete before making 'v2' the active version for function 'fn1'. This wait for completion behavior happens even if the query invokes the function multiple times for processing multiple rows or if the query contains multiple references to the function that is being changed.

Considerations for changing a version of a function:

To change a version of a function, the environment settings that are in effect when the ALTER FUNCTION statement is issued must be the same as the environment settings that are in effect when the version of the function is first created using the CREATE FUNCTION or ALTER FUNCTION statement if one of the following options is specified:

• QUALIFIER
• PACKAGE OWNER
• WLM ENVIRONMENT FOR DEBUG MODE
• OPTHINT
• SQL PATH
• DECIMAL (if the value includes a comma)

Considerations for catalog comments for a routine definition:

When a function definition is replaced, any existing comment in the catalog for the definition is removed. However, when a function definition is regenerated, any existing comment in the catalog for the definition is retained.

Identifier resolution

See SQL procedural language (SQL PL) for information on how names are resolved to columns, variables, or SQL parameters within an SQL routine.

If duplicate names are used for columns, variables, and parameters, qualify the duplicate names by using the table designator for columns, the routine name for parameters, the label name for SQL variables, and the schema name for global variables.

Characteristics of the package that is generated for a function:

The package that is associated with a version of a function is named as follows:

• location is set to the value of the CURRENT SERVER special register
• collection-id (schema) for the package is the same as the schema qualifier of the function
• package-id is the same as the specific name of the function
• version-id is the same as the version identifier for the version of the function

The package is generated using the bind options that correspond to the implicitly or explicitly specified function options. In addition to the corresponding bind options, the package is generated using the following bind options:

• FLAG(I)
• SQLERROR(NOPACKAGE)
• ENABLE(*)

Correspondence of function options to bind command options:

The following table lists options for CREATE FUNCTION and ALTER FUNCTION and the corresponding bind command option. See BIND and REBIND options for packages, plans, and services for information about the BIND command options.

Table 1. Correspondence of function options to bind options

CREATE FUNCTION or ALTER FUNCTION option	bind command option
ACCELERATION WAITFORDATA nnnn.m	ACCELERATIONWAITFORDATA(nnnn.m)
ACCELERATOR accelerator-name	ACCELERATOR(accelerator-name)
APPLICATION ENCODING SCHEME ASCII	ENCODING(ASCII)
APPLICATION ENCODING SCHEME EBCDIC	ENCODING(EBCDIC)
APPLICATION ENCODING SCHEME UNICODE	ENCODING(UNICODE)
ARCHIVE SENSITIVE NO	ARCHIVESENSITIVE(NO)
ARCHIVE SENSITIVE YES	ARCHIVESENSITIVE(YES)
BUSINESS_TIME SENSITIVE NO	BUSTIMESENSITIVE(NO)
BUSINESS_TIME SENSITIVE YES	BUSTIMESENSITIVE(YES)
CURRENT DATA NO	CURRENTDATA(NO)
CURRENT DATA YES	CURRENTDATA(YES)
DYNAMICRULES RUN	DYNAMICRULES(RUN)
DYNAMICRULES BIND	DYNAMICRULES(BIND)
DYNAMICRULES DEFINEBIND	DYNAMICRULES(DEFINEBIND)
DYNAMICRULES DEFINERUN	DYNAMICRULES(DEFINERUN)
DYNAMICRULES INVOKEBIND	DYNAMICRULES(INVOKEBIND)
DYNAMICRULES INVOKERUN	DYNAMICRULES(INVOKERUN)
GET_ACCEL_ARCHIVE NO	GETACCELARCHIVE(NO)
GET_ACCEL_ARCHIVE YES	GETACCELARCHIVE(YES)
ISOLATION LEVEL CS	ISOLATION(CS)
ISOLATION LEVEL RS	ISOLATION(RS)
ISOLATION LEVEL RR	ISOLATION(RR)
ISOLATION LEVEL UR	ISOLATION(UR)
OPTHINT string-constant	OPTHINT(hint-id)
PACKAGE OWNER authorization-name	OWNER(authorization-id)
QUALIFIER schema-name	QUALIFIER(qualifier-name)
QUERY ACCELERATION NONE	QUERYACCELERATION(NONE)
QUERY ACCELERATION ENABLE	QUERYACCELERATION(ENABLE)
QUERY ACCELERATION ENABLE WITH FAILBACK	QUERYACCELERATION(ENABLE WITH FAILBACK)
QUERY ACCELERATION ELIGIBLE	QUERYACCELERATION(ELIGIBLE)
QUERY ACCELERATION ALL	QUERYACCELERATION(ALL)
REOPT ALWAYS	REOPT(ALWAYS)
REOPT NONE	REOPT(NONE)
REOPT ONCE	REOPT(ONCE)
ROUNDING DEC_ROUND_CEILING	ROUNDING(CEILING)
ROUNDING DEC_ROUND_DOWN	ROUNDING(DOWN)
ROUNDING DEC_ROUND_FLOOR	ROUNDING(FLOOR)
ROUNDING DEC_ROUND_HALF_DOWN	ROUNDING(HALFDOWN)
ROUNDING DEC_ROUND_HALF_EVEN	ROUNDING(HALFEVEN)
ROUNDING DEC_ROUND_HALF_UP	ROUNDING(HALFUP)
ROUNDING DEC_ROUND_UP	ROUNDING(UP)
SQL PATH path-specification	PATH(path-specification)
SYSTEM_TIME SENSITIVE NO	SYSTIMESENSITIVE(NO)
SYSTEM_TIME SENSITIVE YES	SYSTIMESENSITIVE(YES)
VALIDATE BIND	VALIDATE(BIND)
VALIDATE RUN	VALIDATE(RUN)
WITH EXPLAIN	EXPLAIN(YES)
WITHOUT EXPLAIN	EXPLAIN(NO)
WITH IMMEDIATE WRITE	IMMEDWRITE(YES)
WITHOUT IMMEDIATE WRITE	IMMEDWRITE(NO)

Application compatibility level considerations for function objects

The application compatibility level controls the adoption and use of new capabilities and enhancements. When an object is created or altered, two separate application compatibility levels are used: one to process the definition of the object, and the other for processing the SQL statements in the object body:

Object definition

The CURRENT APPLICATION COMPATIBILITY special register value is used to process the object definition, except for statements in the object body This application compatibility level is stored in the SYSENVIRONMENT.APPLCOMPAT column. You can use the environment ID value in the catalog definition of the object to locate the SYSENVIRONMENT row with the matching ENVID value. This application compatibility level can be changed when the object is regenerated.

Statements in the object body

The application compatibility level that is implicitly or explicitly specified with the APPLCOMPAT option of the CREATE or ALTER statement is used to process statements in the object body. This application compatibility level is stored in the SYSPACKAGE.APPLCOMPAT column for the package associated with the object definition.

Altering a function definition using a lower application compatibility level than the current definition

If the CURRENT APPLICATION COMPATIBILITY special register value is lower than the application compatibility level of the existing object definition, altering an object might result in an error even if the content of the ALTER statement is valid at the current level. The errors can occur when the existing object definition contains some functionality that requires a higher level than the CURRENT APPLICATION COMPATIBILITY special register setting.

Application compatibility levels for regenerating function objects

For ALTER statements that regenerate objects, the object definition is reprocessed using the application compatibility setting that is specified implicitly or explicitly by the USING APPLICATION COMPATIBILITY clause that follows the REGENERATE keyword. This application compatibility value replaces the existing value in the SYSENVIRONMENT.APPLCOMPAT column for the environment settings associated with the object definition.

If the USING APPLICATION COMPATIBILITY clause is not specified, the existing application compatibility value in the SYSENVIRONMENT.APPLCOMPAT column for the object definition is used to reprocess the text associated with the object definition.

The behavior of the statements in the body remains controlled by the value the existing APPLCOMPAT option of the object.

Invalidation of packages

This statement might invalidate all packages that depend on target objects, and sometimes other related objects through cascading effects, depending on the clauses and keywords specified and other factors. When a version of an SQL function is altered to change certain options that are specified for the active version, all application packages that refer to that function are marked invalid, and those invoking packages require a rebind. This includes changes to certain bind options and routine options that result in the implicit regeneration of the function. These options are marked accordingly in the following table in columns "Change requires rebind of invoking application" and "Change results in implicit regeneration of the entire body of the function." For more information, see Changes that invalidate packages.

Implicit rebind and regeneration

When certain attributes of an SQL function are changed, the body of the function might be rebound or regenerated. The columns "Change results in implicit rebind of non-control statements in the body of the function" and the "Change results in implicit regeneration of the entire body of the function" in the following table summarize when implicit rebind and regeneration occurs when specific options are changed.

Table 2. CREATE FUNCTION and ALTER FUNCTION options that result in rebind or regeneration of the function when changed

CREATE FUNCTION or ALTER FUNCTION option	Change requires rebind of invoking application?	Change results in implicit rebind of non-control statements in the body of the function?	Change results in implicit regeneration of the entire body of the function?
ACCELERATION WAITFORDATA	No	Yes	No
ACCELERATOR	No	Yes	No
ALLOW DEBUG MODE, DISALLOW DEBUG MODE, or DISABLE DEBUG MODE	Yes 1, 2	Yes 1	Yes
APPLICATION ENCODING SCHEME	Yes	Yes	Yes
ARCHIVE SENSITIVE	Yes	Yes	Yes
ASUTIME	Yes	No	No
BUSINESS_TIME SENSITIVE	Yes	Yes	Yes
CURRENT DATA	No	Yes	No
DATE FORMAT	Yes	Yes	Yes
DECIMAL	Yes	Yes	Yes
DYNAMICRULES	No	Yes	No
FOR UPDATE CLAUSE OPTIONAL or FOR UPDATE CLAUSE REQUIRED	Yes	Yes	Yes
GET_ACCEL_ARCHIVE	Yes	Yes	Yes
INHERIT SPECIAL REGISTERS or DEFAULT SPECIAL REGISTERS	Yes	No	No
ISOLATION LEVEL	No	Yes	No
MODIFIES SQL DATA, READS SQL DATA, or CONTAINS SQL	Yes	Yes	Yes
NOT DETERMINISTIC or DETERMINISTIC	No	No	No
OPTHINT	No	Yes	No
PACKAGE OWNER	No	Yes	No
QUALIFIER	No	Yes	No
QUERY ACCELERATION	Yes	Yes	Yes
REOPT	No	Yes	No
ROUNDING	Yes	Yes	Yes
SQL PATH	No	Yes	No
SYSTEM_TIME SENSITIVE	Yes	Yes	Yes
TIME FORMAT	Yes	Yes	Yes
VALIDATE RUN or VALIDATE BIND	No	Yes	No
WITH EXPLAIN or WITHOUT EXPLAIN	No	Yes	No
WITH IMMEDIATE WRITE or WITHOUT IMMEDIATE WRITE	No	Yes	No
WLM ENVIRONMENT FOR DEBUG MODE	Yes	No	No
Note: The function package is rebound or regenerated if a value of ALLOW DEBUG MODE is changed to DISALLOW DEBUG MODE Invoking applications are invalidated if a value of DISALLOW DEBUG MODE is changed to DISABLE DEBUG MODE

Considerations for SQL processor programs:

SQL processor programs (such as SPUFI, the db2z_sql_alterfunctionsqlscalar, and DSNTEP2) might not correctly parse SQL statements in the routine body that are ended with semicolons. These processor programs accept multiple SQL statements as input when each statement is separated with a terminator character. Processor programs that use a semicolon as the SQL statement terminator might truncate an ALTER FUNCTION statement with embedded semicolons and pass only a portion of the statement to Db2. Therefore, you might need to change to SQL terminator character for these processor programs.

Considerations for the SYSENVIRONMENTS catalog table:

An ALTER statement that specifies new environment settings will result in a new row being added to the SYSENVIRONMENTS catalog table. The new row will be added even if an error is subsequently encountered during processing of the statement. Thus, a new SYSENVIRONMENT row might be added to the table even for an ALTER statement that fails.

Dependent objects:

An SQL routine is dependent on objects that are referenced in the routine body.

Altering a function from NOT SECURED to SECURED:

Typically, the security administrator will examine the data that is accessed by a function, ensure that it is secure, and grant the CREATE_SECURE_OBJECT privilege to the user that requires privileges to change the user-defined function to be secured. After the function is changed to SECURED, the security administrator will revoke the CREATE_SECURE_OBJECT privilege from the owner of the function.

The function is considered secure after the ALTER FUNCTION statement is executed. Db2 treats the SECURED attribute as an assertion that declares that the security administrator has established an audit procedure for all changes to the user-defined function. Db2 assumes that such a control audit procedure is in place for all subsequent ALTER FUNCTION statements or changes to external packages.

Packages and statements in the dynamic statement cache that reference the function are invalidated.

Altering a function from SECURED to NOT SECURED:

Packages and statements in the dynamic statement cache that reference the function are invalidated when the function is changed from SECURED to NOT SECURED. An function that is not secured might negatively impact performance if that function accesses data in a table that is using row access control or column access control. To minimize the performance impact, either change the function to use the SECURED option or deactivate row access control or column access control for the table that the function is accessing.

Invoking other user-defined functions in a secure function:

When a secure user-defined function is referenced in an SQL data change statement that references a table that is using row access control or column access control, and if the secure user-defined function invokes other user-defined functions, the nested user-defined functions are not validated as secure. If those nested functions can access sensitive data, the security administrator needs to ensure that those functions are allowed to access sensitive data and should ensure that a change control audit procedure has been established for all changes to those functions.

The SECURE column in the DSN_FUNCTION_TABLE EXPLAIN table:

The SECURE column in the DSN_FUNCTION_TABLE EXPLAIN table indicates if a user-defined function is considered secure.

Altering obfuscated functions:

Obfuscated functions cannot be altered in any way.

Deploying a compiled SQL function:

When a BIND DEPLOY command is issued to deploy a compiled SQL function to a target location, the SECURED and NOT SECURED options are included in the deployment process.

When deploying a compiled SQL function, if a function with the same target name does not exist at the target location, the deployed function is created as a new function at the target location with the same SECURED or NOT SECURED option that is specified (or the default of NOT SECURED is used) in the source function of the deployment.

When deploying a compiled SQL function, if a function with the same target name already exists at the target location, the deployed function is either added as a new version of the function or is used to replace an existing version of the function. The SECURED or NOT SECURED option of the deployed function must be the same as that of the existing function at the target location

Compatibilities:

For compatibility with the CREATE FUNCTION (SQL scalar) statement, the following clause can be specified, but will be ignored:

• LANGUAGE SQL

Optional syntax:

To provide compatibility with the syntax of the CREATE FUNCTION statement, the following options can also be specified:

• SPECIFIC
• PARAMETER CCSID

However, if these options are specified, the value for the option must be the same as the value that is already in effect for the function.

Alternative syntax and synonyms:

To provide compatibility with previous releases of Db2 or other products in the Db2 family, Db2 supports the following keywords:

• VARIANT as a synonym for NOT DETERMINISTIC
• NOT VARIANT as a synonym for DETERMINISTIC
• NULL CALL as a synonym for CALLED ON NULL INPUT
• NOT NULL CALL as a synonym for RETURNS NULL ON NULL INPUT
• TIMEZONE can be specified as an alternative to TIME ZONE