Adding same column to several tables.

Hello,
I have a function to add column to all tables from the list:do$$declare relnam pg_class.relname%TYPE; kur cursor for select c.relname from pg_class as c inner join pg_attribute as a on a.attrelid = c.oid where a.attname = 'some_id' and c.relkind = 'r';begin open kur; LOOP Fetch kur into relnam; exit when not found; EXECUTE 'ALTER TABLE '|| relnam|| ' add column another_id integer default -1'; END LOOP; close kur;END;$$
I have 22 table names returned by the query used by cursor. Whe I run the function it executes for 1.5 minutes. Is there a way of doing it faster?