Re: idea for concurrent seqscans

From: Gaetano Mendola <mendola(at)bigfoot(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: idea for concurrent seqscans
Date: 2005-02-28 14:35:10
Message-ID: 42232C1E.8050802@bigfoot.com
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Tom Lane wrote:
> "Jim C. Nasby" <decibel(at)decibel(dot)org> writes:
>
>>Assuming you're talkning about "You might wonder why we don't order all
>>the regression test queries explicitly to get rid of this issue once and
>>for all. The reason is that that would make the regression tests less
>>useful, not more, since they'd tend to exercise query plan types that
>>produce ordered results to the exclusion of those that don't.", good
>>point. I can think of 2 ways around this:
>
>
>>1) Select into a temptable, then select out of it with an order by
>
>
>>2) Run the output through sort before doing the diff
>
>
>>Is there any reason one of these wouldn't work?
>
>
> Like I said originally, we could certainly devise a solution if we
> needed to. I was just pointing out that this is a nontrivial
> consideration, and I don't want to buy into it if the patch proves
> to offer only marginal performance improvements.
>

I'll bet will not offer only marginal performance improvements. I see some
time my 4-CPU server with 3 CPU in holiday and other CPU working on a long
sequential scan. I hope that this patch, if it works correctly will be used
in future Postgresql version

Regards
Gaetano Mendola

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