Re: [PERFORM] 10x faster sort performance on Skylake CPU vs Ivy Bridge

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От Tom Lane
Тема Re: [PERFORM] 10x faster sort performance on Skylake CPU vs Ivy Bridge
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Msg-id 793.1503673641@sss.pgh.pa.us
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Ответ на [PERFORM] 10x faster sort performance on Skylake CPU vs Ivy Bridge  (Felix Geisendörfer <felix@felixge.de>)
Ответы Re: [PERFORM] 10x faster sort performance on Skylake CPU vs Ivy Bridge  (Peter Geoghegan <pg@bowt.ie>)
Re: [PERFORM] 10x faster sort performance on Skylake CPU vs IvyBridge  (Felix Geisendörfer <felix@felixge.de>)
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=?utf-8?Q?Felix_Geisend=C3=B6rfer?= <felix@felixge.de> writes:
> I recently came across a performance difference between two machines that surprised me:
> ...
> As you can see, Machine A spends 5889ms on the Sort Node vs 609ms on Machine B when looking at the "Exclusive" time
withexplain.depesz.com [3][4]. I.e. Machine B is ~10x faster at sorting than Machine B (for this particular query). 

I doubt this is a hardware issue, it's more likely that you're comparing
apples and oranges.  The first theory that springs to mind is that the
sort keys are strings and you're using C locale on the faster machine but
some non-C locale on the slower.  strcoll() is pretty darn expensive
compared to strcmp() :-(

            regards, tom lane


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