| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
| Cc: | pgsql(at)mohawksoft(dot)com, "Hannu Krosing" <hannu(at)2ndquadrant(dot)com>, Decibel! <decibel(at)decibel(dot)org>, "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, "Pg Hackers" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Block-level CRC checks |
| Date: | 2008-10-01 15:36:44 |
| Message-ID: | 23211.1222875404@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
"Jonah H. Harris" <jonah(dot)harris(at)gmail(dot)com> writes:
> On Wed, Oct 1, 2008 at 10:27 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Your optimism is showing ;-). XLogInsert routinely shows up as a major
>> CPU hog in any update-intensive test, and AFAICT that's mostly from the
>> CRC calculation for WAL records.
> I probably wouldn't compare checksumming *every* WAL record to a
> single block-level checksum.
No, not at all. Block-level checksums would be an order of magnitude
more expensive: they're on bigger chunks of data and they'd be done more
often.
regards, tom lane
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