Hello sorry, I didn't see a link on privatepastebin There is problem in LIMIT, because query without LIMIT returns only a few lines more than query with LIMIT. You can try to materialize query without LIMIT and then to use LIMIT like SELECT * FROM (your query without limit OFFSET 0) x LIMIT 30; Regards Pavel Stehule 2011/7/9 Pavel Stehule <pavel.stehule@xxxxxxxxx>: > Hello > > Is impossible to help you without more detailed info about your problems, > > we have to see a execution plan, we have to see slow query > > Regards > > Pavel Stehule > > 2011/7/9 Jonathan <jonathan@xxxxxxxxxx>: >> Does anyone have any suggestions for my problem? (I have to wonder if I'm >> somehow just not getting peoples attention or what. This is my second >> question this week on a public mailing list that has gotten exactly 0 >> replies) >> >> Jonathan >> >> On 7/5/2011 8:18 PM, Jonathan wrote: >>> >>> I have a query that uses ORDER BY and LIMIT to get a set of image data >>> rows that match a given tag. When both ORDER BY and LIMIT are included >>> for some reason the planner chooses a very slow query plan. Dropping one >>> or the other results in a much faster query going from 4+ seconds -> 30 >>> ms. Database schema, EXPLAIN ANALYZE and other information can be found >>> at http://pgsql.privatepaste.com/31113c27bf Is there a way to convince >>> the planner to use the faster plan when doing both ORDER BY and LIMIT >>> without using SET options or will I need to disable the slow plan >>> options to force the planner to use the fast plan? >>> >>> I found some stuff in the mailing list archives that looks related but I >>> didn't see any fixes. Apparently the planner hopes the merge join will >>> find the LIMIT # of rows fairly quickly but instead it winds up scanning >>> almost the entire table. >> >> -- >> Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) >> To make changes to your subscription: >> http://www.postgresql.org/mailpref/pgsql-performance >> > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
