| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Where does the time go? |
| Date: | 2006-03-23 02:59:52 |
| Message-ID: | 27386.1143082792@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-patches |
"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> I have some odd results from timing two versions of an update query, and
> was hoping to get a better handle on how to interpret this.
You didn't show us the explain analyze results, but I'm betting that a
big part of your issue is that the EXPLAIN ANALYZE instrumentation
overhead is (1) significant and (2) different for the two query plans.
The instrumentation overhead should be about the same for any one plan
node execution, but the two plans could involve very different numbers
of plan node executions ...
regards, tom lane
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