NAME

       ALTER_FUNCTION - change 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 | CURRENT_USER | SESSION_USER }
       ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
           SET SCHEMA new_schema
       ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
           DEPENDS ON EXTENSION extension_name

       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
           PARALLEL { UNSAFE | RESTRICTED | SAFE }
           COST execution_cost
           ROWS result_rows
           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 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

       name
           The name (optionally schema-qualified) of an existing function. If no argument list is
           specified, the name must be unique in its schema.

       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 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.

       extension_name
           The name of the extension that the function is to depend on.

       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 (CREATE_FUNCTION(7)) for more information.

       IMMUTABLE
       STABLE
       VOLATILE
           Change the volatility of the function to the specified setting. See CREATE FUNCTION
           (CREATE_FUNCTION(7)) 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 (CREATE_FUNCTION(7)) for more
           information about this capability.

       PARALLEL
           Change whether the function is deemed safe for parallelism. See CREATE FUNCTION
           (CREATE_FUNCTION(7)) for details.

       LEAKPROOF
           Change whether the function is considered leakproof or not. See CREATE FUNCTION
           (CREATE_FUNCTION(7)) for more information about this capability.

       COST execution_cost
           Change the estimated execution cost of the function. See CREATE FUNCTION
           (CREATE_FUNCTION(7)) for more information.

       ROWS result_rows
           Change the estimated number of rows returned by a set-returning function. See CREATE
           FUNCTION (CREATE_FUNCTION(7)) for more information.

       configuration_parameter
       value
           Add or change 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.

           See SET(7) and Chapter 19 for more information about allowed parameter names and
           values.

       RESTRICT
           Ignored for conformance with the SQL standard.

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 maths:

           ALTER FUNCTION sqrt(integer) SET SCHEMA maths;

       To mark the function sqrt for type integer as being dependent on the extension mathlib:

           ALTER FUNCTION sqrt(integer) DEPENDS ON EXTENSION mathlib;

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

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

       To 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 key word, which is optional in
       PostgreSQL.

SEE ALSO

       CREATE FUNCTION (CREATE_FUNCTION(7)), DROP FUNCTION (DROP_FUNCTION(7))