On October 3, 2006 05:08 am, Alexander Staubo wrote: > On Oct 3, 2006, at 13:25 , Arnaud Lesauvage wrote: > > The problem is that simple select queries with the primary key in > > the WHERE statement take very long to run. > > For example, this query returns only 7 rows and takes about 1 > > second to run ! > > SELECT * FROM table1 WHERE gid in (33,110,65,84,92,94,13,7,68,41); > > This is a very small table, but generally speaking, such queries > benefit from an index; eg., > > create index table1_gid on table1 (gid); gid is is a PRIMARY KEY, so it will already have an index in place. > > Note that PostgreSQL may still perform a sequential scan if it thinks > this has a lower cost, eg. for small tables that span just a few pages. > > > I have run "VACUUM FULL" on this table many times... I don't know > > what to try next ! > > PostgreSQL's query planner relies on table statistics to perform > certain optimizations; make sure you run "analyze table1". > > Alexander. > > ---------------------------(end of broadcast)--------------------------- > TIP 1: if posting/reading through Usenet, please send an appropriate > subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your > message can get through to the mailing list cleanly -- Darcy Buskermolen Command Prompt, Inc. Sales/Support: +1.503.667.4564 || 24x7/Emergency: +1.800.492.2240 PostgreSQL solutions since 1997 http://www.commandprompt.com/
