Horton

Re: Cost of XLogInsert CRC calculations

Tom Lane <tgl@sss.pgh.pa.us>

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Greg Stark <gsstark@mit.edu>
Cc: Bruce Momjian <pgman@candle.pha.pa.us>, Manfred Koizar <mkoi-pg@aon.at>, Mark Cave-Ayland <m.cave-ayland@webbased.co.uk>, pgsql-hackers@postgresql.org
Date: 2005-05-18T05:12:26Z
Lists: pgsql-hackers 
Greg Stark <gsstark@mit.edu> writes:
> Tom Lane <tgl@sss.pgh.pa.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.

			regards, tom lane