---
title: "ALTER FUNCTION"
id: sql-alterfunction
pg_version: "20devel"
---
# 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_ROLE | CURRENT_USER | SESSION_USER }
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
SET SCHEMA new_schema
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
[ NO ] 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
SUPPORT support_function
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 be able to `SET ROLE` to 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. **`DEPENDS ON EXTENSION extension_name`**, **`NO DEPENDS ON EXTENSION extension_name`**
This form marks the function as dependent on the extension, or no longer dependent on that extension if `NO` is specified. A function that's marked as dependent on an extension is dropped when the extension is dropped, even if `CASCADE` is not specified. A function can depend upon multiple extensions, and will be dropped when any one of those extensions is dropped. **`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](sql-createfunction.md) for more information. **`IMMUTABLE`**, **`STABLE`**, **`VOLATILE`**
Change the volatility of the function to the specified setting. See [CREATE FUNCTION](sql-createfunction.md) 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](sql-createfunction.md) for more information about this capability. **`PARALLEL`**
Change whether the function is deemed safe for parallelism. See [CREATE FUNCTION](sql-createfunction.md) for details. **`LEAKPROOF`**
Change whether the function is considered leakproof or not. See [CREATE FUNCTION](sql-createfunction.md) for more information about this capability. **`COST` `execution_cost`**
Change the estimated execution cost of the function. See [CREATE FUNCTION](sql-createfunction.md) for more information. **`ROWS` `result_rows`**
Change the estimated number of rows returned by a set-returning function. See [CREATE FUNCTION](sql-createfunction.md) for more information. **`SUPPORT` `support_function`**
Set or change the planner support function to use for this function. See [Section 36.11](xfunc-optimization.md) for details. You must be superuser to use this option. This option cannot be used to remove the support function altogether, since it must name a new support function. Use `CREATE OR REPLACE FUNCTION` if you need to do that. **`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](sql-set.md) and [Chapter 19](runtime-config.md) 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](sql-createfunction.md), [DROP FUNCTION](sql-dropfunction.md), [ALTER PROCEDURE](sql-alterprocedure.md), [ALTER ROUTINE](sql-alterroutine.md)