Message-ID: <43D8FDB7.10905@archonet.com>
Date: Thu, 26 Jan 2006 16:49:59 +0000
From: Richard Huxton <dev@archonet.com>
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To: Jozsef Szalay <jszalay@storediq.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Incorrect Total runtime Reported by Explain Analyze!?
References: <E387E2E9622FDD408359F98BF183879E2BDE92@dc1.storediq.com>
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Jozsef Szalay wrote:
> 
> I have seen it on occasion that the total runtime reported by explain
> analyze was much higher than the actual time the query needed to
> complete. The differences in my case ranged between 20-120 seconds. I'm
> just curious if anyone else has experienced this and whether there is
> something that I can do to convince explain analyze to report the
> execution time of the query itself rather than the time of its own
> execution. Engine version is 8.1.1.

I think it's down to all the gettime() calls that have to be made to 
measure how long each stage of the query takes. In some cases these can 
take a substantial part of the overall query time. I seem to recall one 
of the BSDs was particularly bad in this respect a couple of years ago. 
Does that sound like your problem?

-- 
   Richard Huxton
   Archonet Ltd