On 7/8/05, Michael Fuhr <mike@xxxxxxxx> wrote: > On Fri, Jul 08, 2005 at 12:04:07PM -0400, Stephen Bowman wrote: > > > > Clearly it needs to use the index =) > > Indeed -- now to figure out why the estimates for index scans are > so high. The row count estimates are almost spot-on, so that's not > it. What are your settings for the following configuration variables? > > shared_buffers > random_page_cost > effective_cache_size > cpu_tuple_cost > cpu_index_tuple_cost > > How much RAM do you have? Have you set shared_buffers and > effective_cache_size accordingly? The default values are pretty > low for most modern equipment; see the following for tips on > choosing appropriate values: > > http://www.powerpostgresql.com/PerfList/ > > You mentioned that you've analyzed the table, but have you also > vacuumed it recently? > > BTW, I should have mentioned earlier that this thread might be > on-topic in pgsql-performance. > > -- > Michael Fuhr > http://www.fuhr.org/~mfuhr/ > This is on a Xeon 3ghz with 2gb of RAM. There are 2 SCSI U/320 disks. For the variables, I have everything defaulted except for: shared_buffers = 20000 effective_cache_size = 68916 I just added random_page_cost=3 and it seems to have fixed it. Do the values I have set for these variables make sense with my hardware? The database is large (~15g). My apologies on the wrong mailing list - next time I'll use -perf. Thanks, --Stephen ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
