CREATE OR REPLACE FUNCTION ff_string_add (t1 text, t2 text) RETURNS text AS $$ BEGIN RETURN t1 || ' ioM0Thu6_fieldseparator_kaeph9Ee ' || t2 ; END; $$ LANGUAGE plpgsql IMMUTABLE RETURNS NULL ON NULL INPUT; CREATE AGGREGATE ff_string_agg ( basetype = text, sfunc = ff_string_add, stype = text );