Re: Very ineffective plan with merge join
Oleg Bartunov <oleg@sai.msu.su>
From: Oleg Bartunov <oleg@sai.msu.su>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Pgsql Hackers <pgsql-hackers@postgresql.org>
Date: 2010-04-16T09:25:46Z
Lists: pgsql-hackers
Attachments
- longquery.sql (text/plain)
On Thu, 15 Apr 2010, Kevin Grittner wrote: > Tom Lane <tgl@sss.pgh.pa.us> wrote: > >> I'm not sure how much it would help to increase the statistics >> targets, but that would be worth trying. Setting statistics to 1000 helps for that particular reduced query, but full query (attached) is out of luck. > > I notice that the scan rowcount estimates are very accurate, there's > that one hash join result that's way off, though. > > What's up with the sort of _accrged7200 (in the slower plan) taking > in 3.5 million rows and putting out 1 row? There's something there > I'm not understanding. > > -Kevin > Regards, Oleg _____________________________________________________________ Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru), Sternberg Astronomical Institute, Moscow University, Russia Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/ phone: +007(495)939-16-83, +007(495)939-23-83