ALTER FUNCTION

ALTER FUNCTION

Changes the definition of a function.

Synopsis

ALTER FUNCTION name ( [ [argmode] [argname] argtype [, ...] ] ) 
   action [, ... ] [RESTRICT]

ALTER FUNCTION name ( [ [argmode] [argname] argtype [, ...] ] )
   RENAME TO new_name

ALTER FUNCTION name ( [ [argmode] [argname] argtype [, ...] ] ) 
   OWNER TO new_owner

ALTER FUNCTION name ( [ [argmode] [argname] argtype [, ...] ] ) 
   SET SCHEMA new_schema

where action is one of:

{CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT}
{IMMUTABLE | STABLE | VOLATILE | [ NOT ] LEAKPROOF}
{[EXTERNAL] SECURITY INVOKER | [EXTERNAL] SECURITY DEFINER}
EXECUTE ON { ANY | MASTER | ALL SEGMENTS }
COST execution_cost
SET configuration_parameter { TO | = } { value | DEFAULT }
SET configuration_parameter FROM CURRENT
RESET configuration_parameter
RESET ALL

Description

ALTER FUNCTION changes the definition of a function.

You must own the function to use ALTER FUNCTION. To change a function's schema, you must also have CREATE privilege on the new schema. To alter the owner, you must also be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the function's schema. (These restrictions enforce that altering the owner does not do anything you could not do by dropping and recreating the function. However, a superuser can alter ownership of any function anyway.)

Parameters

name
The name (optionally schema-qualified) of an existing function.
argmode
The mode of an argument: either IN, OUT, INOUT, or VARIADIC. If omitted, the default is IN. Note that ALTER FUNCTION does not actually pay any attention to OUT arguments, since only the input arguments are needed to determine the function's identity. So it is sufficient to list the IN, INOUT, and VARIADIC arguments.
argname
The name of an argument. Note that ALTER FUNCTION does not actually pay any attention to argument names, since only the argument data types are needed to determine the function's identity.
argtype
The data type(s) of the function's arguments (optionally schema-qualified), if any.
new_name
The new name of the function.
new_owner
The new owner of the function. Note that if the function is marked SECURITY DEFINER, it will subsequently execute as the new owner.
new_schema
The new schema for the function.
CALLED ON NULL INPUT
RETURNS NULL ON NULL INPUT
STRICT
CALLED ON NULL INPUT changes the function so that it will be invoked when some or all of its arguments are null. RETURNS NULL ON NULL INPUT or STRICT changes the function so that it is not invoked if any of its arguments are null; instead, a null result is assumed automatically. See CREATE FUNCTION for more information.
IMMUTABLE
STABLE
VOLATILE
Change the volatility of the function to the specified setting. See CREATE FUNCTION for details.
[ EXTERNAL ] SECURITY INVOKER
[ EXTERNAL ] SECURITY DEFINER
Change whether the function is a security definer or not. The key word EXTERNAL is ignored for SQL conformance. See CREATE FUNCTION for more information about this capability.
LEAKPROOF
Change whether the function is considered leakproof or not. See CREATE FUNCTION for more information about this capability.
EXECUTE ON ANY
EXECUTE ON MASTER
EXECUTE ON ALL SEGMENTS
The EXECUTE ON attributes specify where (master or segment instance) a function executes when it is invoked during the query execution process.
EXECUTE ON ANY (the default) indicates that the function can be executed on the master, or any segment instance, and it returns the same result regardless of where it is executed. Greenplum Database determines where the function executes.
EXECUTE ON MASTER indicates that the function must execute only on the master instance.
EXECUTE ON ALL SEGMENTS indicates that the function must execute on all primary segment instances, but not the master, for each invocation. The overall result of the function is the UNION ALL of the results from all segment instances.
For more information about the EXECUTE ON attributes, see CREATE FUNCTION.
COST execution_cost
Change the estimated execution cost of the function. See CREATE FUNCTION for more information.
configuration_parameter
value
Set or change the value of a configuration parameter when the function is called. If value is DEFAULT or, equivalently, RESET is used, the function-local setting is removed, and the function executes with the value present in its environment. Use RESET ALL to clear all function-local settings. SET FROM CURRENT saves the value of the parameter that is current when ALTER FUNCTION is executed as the value to be applied when the function is entered.
RESTRICT
Ignored for conformance with the SQL standard.

Notes

Greenplum Database has limitations on the use of functions defined as STABLE or VOLATILE. See CREATE FUNCTION for more information.

Examples

To rename the function sqrt for type integer to square_root:

ALTER FUNCTION sqrt(integer) RENAME TO square_root;

To change the owner of the function sqrt for type integer to joe:

ALTER FUNCTION sqrt(integer) OWNER TO joe;

To change the schema of the function sqrt for type integer to math:

ALTER FUNCTION sqrt(integer) SET SCHEMA math;

To adjust the search path that is automatically set for a function:

ALTER FUNCTION check_password(text) RESET search_path;

Compatibility

This statement is partially compatible with the ALTER FUNCTION statement in the SQL standard. The standard allows more properties of a function to be modified, but does not provide the ability to rename a function, make a function a security definer, or change the owner, schema, or volatility of a function. The standard also requires the RESTRICT key word, which is optional in Greenplum Database.