2012/11/6 Pedro Jiménez Pérez <p.jimenez@xxxxxxxxxxxx> > Ok, here we go: > > I'm using postgresql version 8.0 > > Here is my query that is too slow: http://explain.depesz.com/s/GbQ Well, I would start with a note, that 8.0 is not supported anymore: http://www.postgresql.org/support/versioning/ Please, consider upgrading your instance. Also, it is not handy to provide schema details here and anonymize the EXPLAIN output. Here's the visualization of your initial plan: http://explain.depesz.com/s/AOAN The following join: (ism_floatvalues.id_signal = ism_signal.id_signal) is wrongly estimated by the planner (row 3 of the above explain visualization). It looks like NestedLoop join with IndexScan over ism_floatvalues_index_idsignal_timestamp might do a better job. Try the following: ALTER TABLE ism_floatvalues ALTER COLUMN id_signal SET STATISTICS 1000; /* 1000 is maximum for 8.0 */ ANALYZE ism_floatvalues; Let me know if it helps. -- Victor Y. Yegorov -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
