On Thu, Sep 09, 2010 at 11:16:36AM -0400, Tom Lane wrote: > Henk van Lingen <H.G.K.vanLingen@xxxxx> writes: > > On Thu, Sep 09, 2010 at 10:50:52AM -0400, Tom Lane wrote: > >>>> Well, there's your problem: the planner is off by a factor of about 500 > >>>> on its estimate of the number of rows matching this query, and that's > >>>> what's causing it to pick the wrong plan. What you need to look into > >>>> is getting that estimate to be more in sync with reality. Probably > >>>> increasing the stats target for the message column would help. > > > But how can I get sane estimates for syslog data? Some searchstrings will > > result in only a few hits, others in thousands of records or more. > > That's what ANALYZE is for ... Yes, off course. But I don't see how the most_common_vals & freqs and the histogram_bounds for a text field with syslog data make any sense when doing doing a search for a substring. Increasing the number of entries in those stats lists doesn't make any sense also, i presume. Those stats should be based on analysis of the to_tsvector index, to have any meaning, i think. Today I will look into the multicolumn index suggestion. Regards, -- Henk van Lingen, ICT-SC Netwerk & Telefonie, (o- -+ Universiteit Utrecht, Jenalaan 18a, room 0.12 /\ | phone: +31-30-2538453 v_/_ | http://henk.vanlingen.net/ http://www.tuxtown.net/netiquette/ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
