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Re: explain analyze query execution time

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <rudyar(dot)cortes(at)gmail(dot)com>,<pgsql-hackers(at)postgresql(dot)org>
Subject: Re: explain analyze query execution time
Date: 2011-11-22 05:58:57
Message-ID: 4ECAE5C2020000250004336D@gw.wicourts.gov (view raw or flat)
Thread:
Lists: pgsql-hackers
Rudyar  wrote:
 
> I try to get the execution time of a query workload. I try using
> explain analyze but this time is allways higher than the execution
> time of a query across a client like pgadmin3
> 
> what is the reason about that difference?
 
It's the "observer effect" -- there is a cost to the timing,
counting, measuring, and reporting which is done by EXPLAIN ANALYZE,
which distorts what is being measured.  It's just about impossible to
avoid entirely.
 
-Kevin

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