## ALTER FUNCTION

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 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.

`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 automatically dropped when the extension 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.html) for more information.

`IMMUTABLE`  
`STABLE`  
`VOLATILE`

 Change the volatility of the function to the specified setting. See [CREATE FUNCTION](sql-createfunction.html) 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.html) for more information about this capability.

`PARALLEL`

 Change whether the function is deemed safe for parallelism. See [CREATE FUNCTION](sql-createfunction.html) for details.

`LEAKPROOF`

 Change whether the function is considered leakproof or not. See [CREATE FUNCTION](sql-createfunction.html) for more information about this capability.

`COST` *`execution_cost`*

 Change the estimated execution cost of the function. See [CREATE FUNCTION](sql-createfunction.html) for more information.

`ROWS` *`result_rows`*

 Change the estimated number of rows returned by a set-returning function. See [CREATE FUNCTION](sql-createfunction.html) for more information.

`SUPPORT` *`support_function`*

 Set or change the planner support function to use for this function. See [Section 38.11](xfunc-optimization.html) 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.html) and [Chapter 20](runtime-config.html) 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.html), [DROP FUNCTION](sql-dropfunction.html), [ALTER PROCEDURE](sql-alterprocedure.html), [ALTER ROUTINE](sql-alterroutine.html)

