Re: Explain analyze time overhead - Mailing list pgsql-performance

From Bruce Momjian
Subject Re: Explain analyze time overhead
Date
Msg-id 20131210215944.GB14636@momjian.us
Whole thread Raw
In response to Re: Explain analyze time overhead  (salah jubeh <s_jubeh@yahoo.com>)
List pgsql-performance
On Tue, Dec 10, 2013 at 01:53:54PM -0800, salah jubeh wrote:
> Thanks for the link, I find it very useful,  unfortunatly I am using 9.1.11
> version.
>
> After digging a little bit, I find out that the gettimeofday is indeed a little
> bit slower on this particular machine than other machines, but it is not that
> significanat difference. The query I am running is not optimized, and for some
> reason the material operator is the one which causes most of the overhead. The
> whole issue is due to cross colums statistics and highly correlated predicates,
> the number of estimated records are much less than the actual number.  Still, I
> did not understand completly, why the material operator consume about 9 minutes
> when I run explain analyze. i.e how many times we call gettimeofday for the
> material operator -I need to calculate this-? Finally, for testing purposes, I
> have disabled material  and the query execution time dropped from 1 minute to
> 12 second.

The executable is not tied to any particular Postgres version, so you
could get the 9.3 binary and just use that.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +


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