In response to Matthew <matthew@xxxxxxxxxxx>: > On Fri, 30 Nov 2007, cluster wrote: > > Can anyone explain the following odd behavior? > > I have a query that completes in about 90 ms. If I append LIMIT to the > > very end, eg. "LIMIT 500" the evaluation time increases to about 800 ms. > > How can performance get *worse* by giving the database the option to > > stop the evaluation earlier (when it reaches the output 500 rows)? > > The planner doesn't always get it right. Simple. > > Have you done a "VACUUM FULL ANALYSE" recently? I don't know about the "FULL" part ... but certainly an ANALYZE. Please post EXPLAIN ANALYZE output for the two queries. -- Bill Moran Collaborative Fusion Inc. http://people.collaborativefusion.com/~wmoran/ wmoran@xxxxxxxxxxxxxxxxxxxxxxx Phone: 412-422-3463x4023 **************************************************************** IMPORTANT: This message contains confidential information and is intended only for the individual named. If the reader of this message is not an intended recipient (or the individual responsible for the delivery of this message to an intended recipient), please be advised that any re-use, dissemination, distribution or copying of this message is prohibited. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. E-mail transmission cannot be guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender therefore does not accept liability for any errors or omissions in the contents of this message, which arise as a result of e-mail transmission. **************************************************************** ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
