How to Safely Drop PostgreSQL Functions Without Knowing Their Parameters?

Dropping Functions Without Parameter Knowledge

In Postgres, managing functions stored in a text file can be challenging when adding or removing parameters to existing functions. To address this issue, a wildcard method exists to drop all functions with a specific name, regardless of the number or type of parameters.

Basic Query

Execute the following query to generate DDL statements for dropping all functions with a specific name:

SELECT 'DROP FUNCTION ' || oid::regprocedure
FROM pg_proc
WHERE proname = 'my_function_name'
AND pg_function_is_visible(oid);

Replace 'my_function_name' with your actual function name (case-sensitive and without double-quotes). This query returns a list of DROP FUNCTION statements with the correct parameter types for all overloads of the function.

Function Approach

For immediate execution of the drop statements, consider creating a PL/pgSQL function:

CREATE OR REPLACE FUNCTION f_delfunc(_name text, OUT functions_dropped int)
LANGUAGE plpgsql AS
$func$
DECLARE
   _sql text;
BEGIN
   SELECT count(*)::int
        , 'DROP FUNCTION ' || string_agg(oid::regprocedure::text, '; DROP FUNCTION ')
   FROM pg_catalog.pg_proc
   WHERE proname = _name
   AND pg_function_is_visible(oid)
   INTO functions_dropped, _sql;

   IF functions_dropped > 0 THEN
     EXECUTE _sql;
   END IF;
END
$func$;

To drop all functions named 'my_function_name':

SELECT f_delfunc('my_function_name');

The function will return the number of functions dropped.

Considerations

• This method drops all functions with the specified name, regardless of their owner or schema.
• Be cautious when using this method as it can lead to unintended function removals.
• For versions older than Postgres 9.1, slight modifications are necessary. Consult the answer's edit history for details.

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