<font size="-1"><font face="Arial">It seems to work fine (same execution plan and less duration) after :<br /> -
settingdefault_statistics_target to 100<br /> - full vacuum with analyze<br /> - reindexdb<br /><br /> Thanks.<br
/></font></font><br/><br /> -------- Message original --------<br /> Sujet : Re: [PERFORM] Two different execution plan
forthe same request<br /> De : Guillaume Smet <a class="moz-txt-link-rfc2396E"
href="mailto:guillaume.smet@gmail.com"><guillaume.smet@gmail.com></a><br/> Pour : JOUANIN Nicolas (44) <a
class="moz-txt-link-rfc2396E"
href="mailto:nicolas.jouanin@dgfip.finances.gouv.fr"><nicolas.jouanin@dgfip.finances.gouv.fr></a><br/> Copie à :
YebHavinga <a class="moz-txt-link-rfc2396E" href="mailto:yebhavinga@gmail.com"><yebhavinga@gmail.com></a>, <a
class="moz-txt-link-abbreviated"href="mailto:pgsql-performance@postgresql.org">pgsql-performance@postgresql.org</a><br
/>Date : 07/07/2010 10:59<br /><blockquote cite="mid:AANLkTimrF-p7o2iFzRcRFhH1hPbLT85SVoR6gxynKeRp@mail.gmail.com"
type="cite"><prewrap="">Hi Nicolas,
On Wed, Jul 7, 2010 at 10:47 AM, JOUANIN Nicolas (44)
<a class="moz-txt-link-rfc2396E"
href="mailto:nicolas.jouanin@dgfip.finances.gouv.fr"><nicolas.jouanin@dgfip.finances.gouv.fr></a>wrote:
</pre><blockquotetype="cite"><pre wrap="">There were no modification made on the database except a restart yesterday
eveningand a vacuumdb --analyse ran at night. </pre></blockquote><pre wrap="">
It's not really surprising considering you probably kept the
default_statistics_target to 10 (it's the default in 8.3).
Consider raising it to 100 in your postgresql.conf (100 is the default
for newer versions), then reload, and run a new ANALYZE.
You might need to set it higher on specific columns if you have a lot
of data and your data distribution is weird.
And, btw, please upgrade to the latest 8.3.x.
HTH
</pre></blockquote><br />