-- -- acs_message__first_ancestor/1 -- create or replace function acs_message__first_ancestor( integer ) returns int4 as $$ declare p_message_id alias for $1; v_message_id acs_messages.message_id%TYPE; v_ancestor_sk varbit; begin select tree_ancestor_key(tree_sortkey, 1) into v_ancestor_sk from acs_messages where message_id = p_message_id; select message_id into v_message_id from acs_messages where tree_sortkey = v_ancestor_sk; return v_message_id; end;$$ language plpgsql;