| From: | Gregory Stark <stark(at)enterprisedb(dot)com> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
| Cc: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bruce Momjian <bruce(at)momjian(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, Greg Stark <greg(dot)stark(at)enterprisedb(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Block-level CRC checks |
| Date: | 2008-12-15 17:16:29 |
| Message-ID: | 87ej09pdea.fsf@oxford.xeocode.com |
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| Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Jonah H. Harris escribió:
>> Now, in the case where hint bits have been updated and a WAL record is
>> required because the buffer is being flushed, requiring the WAL to be
>> flushed up to that point may be a killer on performance. Has anyone
>> tested it?
>
> I didn't measure it but I'm sure it'll be plenty slow.
How hard would it be to just take an exclusive lock on the page when setting
all these hint bits? It might be a big performance hit but it would only
affect running with CRC enabled and we can document that. And it wouldn't
involve contorting the existing code much.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Ask me about EnterpriseDB's On-Demand Production Tuning
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