ALTER FUNCTION name ( [ type [, ...] ] ) RENAME TO newname ALTER FUNCTION name ( [ type [, ...] ] ) OWNER TO newowner
The name (optionally schema-qualified) of an existing function.
The data type of an argument of the function.
The new name of the function.
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.
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;
There is an ALTER FUNCTION statement in the SQL standard, but it does not provide the option to rename the function or change the owner.