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Message-ID: <9e4684ce0511120114m32254efen2faa6563146db202@mail.gmail.com>
Date: Sat, 12 Nov 2005 10:14:49 +0100
From: hubert depesz lubaczewski <depesz@gmail.com>
To: dwinner-lists@att.net
Subject: Re: slow queries after ANALYZE
Cc: pgsql-performance@postgresql.org
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On 11/11/05, DW <dwinner-lists@att.net> wrote:
>
> I'm perplexed. I'm trying to find out why some queries are taking a long
> time, and have found that after running analyze, one particular query
> becomes slow.
>

i have had exactly the same problem very recently.
what helped? increasing statistics on come column.
which ones?
make:
explain analyze <your select>;
and check in which situations you gget the biggest change of "estiamted
rows" and "actual rows".
then check what this particular part of your statement is touching, and
increase appropriate statistics.

depesz

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On 11/11/05, <b class=3D"gmail_sendername">DW</b> &lt;<a href=3D"mailto:dwi=
nner-lists@att.net">dwinner-lists@att.net</a>&gt; wrote:<div><span class=3D=
"gmail_quote"></span><blockquote class=3D"gmail_quote" style=3D"border-left=
: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1e=
x;">
I'm perplexed. I'm trying to find out why some queries are taking a long<br=
>time, and have found that after running analyze,&nbsp;&nbsp;one particular=
 query<br>becomes slow.<br></blockquote></div><br>
i have had exactly the same problem very recently.<br>
what helped? increasing statistics on come column.<br>
which ones?<br>
make:<br>
explain analyze &lt;your select&gt;;<br>
and check in which situations you gget the biggest change of &quot;estiamte=
d rows&quot; and &quot;actual rows&quot;.<br>
then check what this particular part of your statement is touching, and inc=
rease appropriate statistics.<br>
<br>
depesz<br>

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