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Re: TCP network cost

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Ross J(dot) Reedstrom" <reedstrm(at)rice(dot)edu>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: TCP network cost
Date: 2009-02-23 21:17:00
Message-ID: 27042.1235423820@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"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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