reference/sql/ALTER-FUNCTION.html.md.erb

---
title: ALTER FUNCTION
---

Changes the definition of a function.

## Synopsis<a id="alterfunction__section2"></a>

``` pre
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:

``` pre
{CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT}
{IMMUTABLE | STABLE | VOLATILE}
{[EXTERNAL] SECURITY INVOKER | [EXTERNAL] SECURITY DEFINER}
```

## 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<a id="alterfunction__section4"></a>

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

 *argmode*   
The mode of an argument: either `IN`, `OUT`, or `INOUT`. 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` and `INOUT` 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.

RESTRICT  
Ignored for conformance with the SQL standard.

## Notes

HAWQ has limitations on the use of functions defined as `STABLE` or `VOLATILE`. See /3/4 for more information.

## Examples<a id="alterfunction__section6"></a>

To rename the function `sqrt` for type `integer` to `square_root`:

``` pre
ALTER FUNCTION sqrt(integer) RENAME TO square_root;
```

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

``` pre
ALTER FUNCTION sqrt(integer) OWNER TO joe;
```

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

``` pre
ALTER FUNCTION sqrt(integer) SET SCHEMA math;
```

## 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 HAWQ.

## See Also

/3/4, /3/4