Re: Very ineffective plan with merge join - Mailing list pgsql-hackers

From Oleg Bartunov
Subject Re: Very ineffective plan with merge join
Date
Msg-id Pine.LNX.4.64.1004161320260.7097@sn.sai.msu.ru
Whole thread Raw
In response to Re: Very ineffective plan with merge join  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
List pgsql-hackers
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

pgsql-hackers by date:

Previous
From: Simon Riggs
Date:
Subject: Re: testing HS/SR - 1 vs 2 performance
Next
From: Oleg Bartunov
Date:
Subject: Re: Very ineffective plan with merge join