Re: Cost of XLogInsert CRC calculations

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, Manfred Koizar <mkoi-pg(at)aon(dot)at>, Mark Cave-Ayland <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Cost of XLogInsert CRC calculations
Date: 2005-05-18 05:24:15
Message-ID: 200505180524.j4I5OF803426@candle.pha.pa.us
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Tom Lane wrote:
> Greg Stark <gsstark(at)mit(dot)edu> writes:
> > Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> >> Do we know that? The results I showed put at least one fundamentally
> >> 32bit platform (the PowerBook I'm typing this on) at dead par for 32bit
> >> and 64bit CRCs.
>
> > Wait, par for 32-bit CRCs? Or for 64-bit CRCs calculated using 32-bit ints?
>
> Right, the latter. We haven't actually tried to measure the cost of
> plain 32bit CRCs... although I seem to recall that when we originally
> decided to use 64bit, someone put up some benchmarks purporting to
> show that there wasn't much difference.

OK, thanks. I didn't know that.

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