From: | Camilo Porto <camiloporto(at)hotmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: URGENT HELP about 'duration' stats |
Date: | 2007-10-27 14:10:06 |
Message-ID: | BLU111-W4F245D9D14469DA3F8AA8BC970@phx.gbl |
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Lists: | pgsql-hackers |
[Camilo Porto]
> To: camiloporto(at)hotmail(dot)com
> CC: pgsql-hackers(at)postgresql(dot)org
> Subject: Re: [HACKERS] URGENT HELP about 'duration' stats
> Date: Fri, 26 Oct 2007 23:06:22 -0400
> From: tgl(at)sss(dot)pgh(dot)pa(dot)us
>
> Camilo Porto <camiloporto(at)hotmail(dot)com> writes:
> > The problem I have encountered is that the sum of executor's
> > duration time is, *sometimes*, bigger than the total time interval in
> > which the statements had been executed!! And this makes no sense!
>
> Umm ... why not? If you have, say, two queries executing in parallel
> for 1 second, they'll each report a duration: of 1 second, thus summing
> to 2 seconds, but the elapsed time was only 1 second.
>
> If you don't see that always, then your benchmark program isn't trying
> very hard to run more than one query in parallel ...
This really make sense, but let me add some questions:
The parallelism happens even if my PC has only one processor?
Each query is executed in a separeted Thread?
I am simulating only 1 client with the Benchmark. Can 1 Client submit parallel queries, in single-processor enviroment?
Many Thanks
>
> regards, tom lane
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