Thanks so much for that info, Tom! On Jan 29, 8:00 pm, t...@xxxxxxxxxxxxx (Tom Lane) wrote: > "Angva" <ang...@xxxxxxxxx> writes: > > Our company's application runs searches with "like" where clauses, for > > example: "where id like '38F20A%'". This query once ran in under 10 ms, > > but since upgrading from 8.1.3 to 8.2.0, it now takes about 500 ms to > > run. The problem appears to be that the planner does not want to use an > > index since the upgrade, for "like" queries. > > We experimented with planner cost constants, and we even tried setting > > enable_seqscan to false. A seq scan was done every time. > > If it won't do it even with seqscan off, then it can't, which most > likely means that you mistakenly picked a non-C locale for the new > installation. You can either fix that (requiring re-initdb :-() or > provide a "pattern_ops" index that's not subject to locale oddities. > Non-C locales tend to impose a sort ordering that's not suited for > LIKE pattern matching. Seehttp://www.postgresql.org/docs/8.2/static/indexes-opclass.html > > regards, tom lane > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq
