Re: explain analyze reports that my queries are fast but they run very slowly - Mailing list pgsql-performance

From Tom Lane
Subject Re: explain analyze reports that my queries are fast but they run very slowly
Date
Msg-id 19936.1356644001@sss.pgh.pa.us
Whole thread Raw
In response to explain analyze reports that my queries are fast but they run very slowly  (Nikolas Everett <nik9000@gmail.com>)
Responses Re: explain analyze reports that my queries are fast but they run very slowly  (Nikolas Everett <nik9000@gmail.com>)
List pgsql-performance
Nikolas Everett <nik9000@gmail.com> writes:
> We straced the backend during the explain and it looked like the open
> commands were taking several seconds each.

Kind of makes me wonder if you have a whole lot of tables ("whole lot"
in this context probably means tens of thousands) and are storing the
database on a filesystem that doesn't scale well to lots of files in one
directory.  If that's the explanation, the reason the 8.3 installation
was okay was likely that it was stored on a more modern filesystem.

BTW, please keep the list cc'd on replies.

            regards, tom lane


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