Re: TCP network cost

From: "Ross J(dot) Reedstrom" <reedstrm(at)rice(dot)edu>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: TCP network cost
Date: 2009-02-24 17:02:01
Message-ID: 20090224170201.GA25420@cooker
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Excellent. I'll take a look at this and report back here.

Ross

On Mon, Feb 23, 2009 at 04:17:00PM -0500, Tom Lane wrote:
> "Ross J. Reedstrom" <reedstrm(at)rice(dot)edu> writes:
> > Summary: C client and large-object API python both send bits in
> > reasonable time, but I suspect there's still room for improvement in
> > libpq over TCP: I'm suspicious of the 6x difference. Detailed analysis
> > will probably find it's all down to memory allocation and extra copying
> > of bits around (client side)
>
> I wonder if the backend isn't contributing to the problem too. It chops
> its sends up into 8K units, which doesn't seem to create huge overhead
> in my environment but maybe it does in yours. It'd be interesting to see
> what results you get from the attached quick-and-dirty patch (against
> HEAD, but it should apply back to at least 8.1).
>
> regards, tom lane

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