Re: 512,600ms query becomes 7500ms... but why? Postgres 8.3 query planner quirk? - Mailing list pgsql-performance

Kevin Grittner wrote:

Bryce Nesbitt <bryce2@obviously.com> wrote: 

I've got a very slow query, which I can make faster by doing
something seemingly trivial.    

 
Out of curiosity, what kind of performance do you get with?:
EXPLAIN ANALYZE
SELECT contexts.context_key FROM contexts JOIN articles ON (articles.context_key = contexts.context_key) JOIN matview_82034 ON (matview_82034.context_key =                        contexts.context_key) WHERE EXISTS       (         SELECT *           FROM article_words           JOIN words using (word_key)           WHERE context_key = contexts.context_key             AND word = 'insider'       )   AND EXISTS       (         SELECT *           FROM article_words           JOIN words using (word_key)           WHERE context_key = contexts.context_key             AND word = 'trading'       )   AND EXISTS       (         SELECT *           FROM virtual_ancestors a           JOIN bp_categories ON (bp_categories.context_key =                                  a.ancestor_key)           WHERE a.context_key = contexts.context_key             AND lower(bp_categories.category) = 'law'       )   AND articles.indexed
; 

512,600ms query becomes 225,976ms.  Twice as fast on pos
Definitely not beating the 7500ms version.
PostgreSQL 8.3.4