> Rod, he has a hierarchy of genres. Genre 1 has 6379 child genres and a > book can be in more than one of these.
bookgenres.genre_id = genre_children.genre_child_id AND genre_children.genre_id = 1 I see, sorry. I didn't notice the genre_child_id in the where clause. First glance had them all as genre_id. When I run into this I usually create a 3rd table managed by triggers that would relate the book to all genre entries. Insert takes a little longer, but the selects can still be very quick. The below plpgsql forces the kind of algorithm we wish the planner could choose. It should be fairly quick irregardless of dataset. CREATE OR REPLACE FUNCTION book_results(numeric) RETURNS SETOF numeric AS ' DECLARE v_genre ALIAS FOR $1; v_limit integer = 10; t_rows RECORD; v_transmitted integer = 0; v_transmitted_values numeric = ARRAY; BEGIN FOR t_rows IN SELECT book_id FROM bv_bookgenres AS b JOIN bv_genre_children AS g ON (b.genre_id = g.genre_child_id) WHERE g.genre_id = v_genre LOOP -- If this is a new value, transmit it to the end user IF NOT t_rows.book_id = ANY(v_transmitted_values) THEN v_transmitted_values := array_append(v_transmitted_values, t_rows.book_id); v_transmitted := v_transmitted + 1; RETURN NEXT t_rows.book_id; END IF; EXIT WHEN v_transmitted >= v_limit; END LOOP; RETURN; END; ' LANGUAGE plpgsql; EXPLAIN ANALYZE SELECT * FROM book_results(1); SELECT * FROM book_results(1); ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings