| From: | Florian Pflug <fgp(at)phlo(dot)org> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | "Pierre C" <lists(at)peufeu(dot)com>, "Greg Stark" <gsstark(at)mit(dot)edu>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Bruce Momjian" <bruce(at)momjian(dot)us>, pgsql-hackers(at)postgresql(dot)org, singh(dot)gurjeet(at)gmail(dot)com |
| Subject: | Re: Re: [RFC][PATCH]: CRC32 is limiting at COPY/CTAS/INSERT ... SELECT + speeding it up |
| Date: | 2010-06-07 12:10:30 |
| Message-ID: | B0CDD01A-6928-4A92-80D3-E7A728480F7B@phlo.org |
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| Lists: | pgsql-hackers |
On Jun 7, 2010, at 12:45 , Andres Freund wrote:
> On Monday 07 June 2010 12:37:13 Pierre C wrote:
>>> On Sunday 30 May 2010 18:29:31 Greg Stark wrote:
>>>> On Sun, May 30, 2010 at 4:54 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>>> I read through that thread and couldn't find much discussion of
>>>>> alternative CRC implementations --- we spent all our time on arguing
>>>>> about whether we needed 64-bit CRC or not.
>>
>> SSE4.2 has a hardware CRC32 instruction, this might be interesting to
>> use...
> Different polynom unfortunately...
Since only the WAL uses CRC, I guess the polynomial could be changed though. pg_upgrade for example shouldn't care.
RFC3385 compares different checksumming methods for use in iSCSI, and CRC32c (which uses the same polynomial as the SSE4.2 instruction) wins. Here's
a link: http://www.faqs.org/rfcs/rfc3385.html
best regards,
Florian Pflug
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