ALTER FUNCTION SQL - Language Statements ALTER FUNCTION change the definition of a function ALTER FUNCTION ALTER FUNCTION name ( [ type [, ...] ] ) action [, ... ] [ RESTRICT ] ALTER FUNCTION name ( [ type [, ...] ] ) RENAME TO newname ALTER FUNCTION name ( [ type [, ...] ] ) OWNER TO newowner where action is one of: CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT IMMUTABLE | STABLE | VOLATILE [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER ALTER FUNCTION changes the definition of a function. name The name (optionally schema-qualified) of an existing function. type The data type of an argument of the function. newname The new name of the function. newowner The new owner of the function. To change the owner of a function, you must be a superuser. Note that if the function is marked SECURITY DEFINER, it will subsequently execute as the new owner. 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 always returns null if any of its arguments are null. See for more information. IMMUTABLE STABLE VOLATILE Change the volatility of the function to the specified type. See for more information about function volatility. 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 for more information about this capability. RESTRICT Ignored for conformance with the SQL standard. 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; 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 or volatility of a function. The standard also requires the RESTRICT key word; it is optional in PostgreSQL.