--
-- trigger_exists/2
--
create or replace function trigger_exists(
  character varying,
  character varying
) returns bool as $$

declare 
        trigger_name    alias for $1;
        on_table        alias for $2;
begin
        return count(*) > 0
          from pg_class c, pg_trigger t
         where c.relname = lower(on_table)
           and c.oid = t.tgrelid
           and t.tgname = lower(trigger_name);

end;$$ language plpgsql;