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Re: Incorrect Total runtime Reported by Explain Analyze!?

From: Richard Huxton <dev(at)archonet(dot)com>
To: Jozsef Szalay <jszalay(at)storediq(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Incorrect Total runtime Reported by Explain Analyze!?
Date: 2006-01-26 16:49:59
Message-ID: 43D8FDB7.10905@archonet.com (view raw or flat)
Thread:
Lists: pgsql-performance
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

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