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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 | INITPLAN }
    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 the 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 the CREATE privilege on the function’s schema. These restrictions enforce that altering the owner doesn’t do anything you couldn’t do by dropping and recreating the function. However, a superuser can alter ownership of any function anyway.

Parameters

Parameter Description

name

The name (optionally schema-qualified) of an existing function

argmode

The mode of an argument: 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 types 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

Changes the function so that it will be invoked when some or all of its arguments are null

RETURNS NULL ON NULL INPUT

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

STRICT

See RETURNS NULL ON NULL INPUT

IMMUTABLE

Changes the volatility of the function to the specified setting

STABLE

Changes the volatility of the function to the specified setting

VOLATILE

Changes the volatility of the function to the specified setting

[ EXTERNAL ] SECURITY INVOKER

[ EXTERNAL ] SECURITY DEFINER

Changes whether the function is a security definer or not. The keyword EXTERNAL is ignored for SQL conformance

LEAKPROOF

Changes whether the function is considered leakproof or not

COST <execution_cost>

Changes the estimated execution cost of the function

configuration_parameter, value

Adds or changes the assignment to be made to a configuration parameter when the function is called. If value is DEFAULT or, equivalently, RESET is used, the function-local setting is removed, so that 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

Examples

Rename the function sqrt for type integer to square_root:

ALTER FUNCTION sqrt(integer) RENAME TO square_root;

Change the owner of the function sqrt for type integer to joe:

ALTER FUNCTION sqrt(integer) OWNER TO joe;

Change the schema of the function sqrt for type integer to maths:

ALTER FUNCTION sqrt(integer) SET SCHEMA maths;

Adjust the search path that is automatically set for a function:

ALTER FUNCTION check_password(text) SET search_path = admin, pg_temp;

Disable automatic setting of search_path for a function:

ALTER FUNCTION check_password(text) RESET search_path;

The function will now execute with whatever search path is used by its caller.

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, attach configuration parameter values to a function, or change the owner, schema, or volatility of a function. The standard also requires the RESTRICT keyword, which is optional in PostgreSQL.

See also

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ALTER FOREIGN TABLE
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ALTER GROUP