| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Gregory Stark <stark(at)enterprisedb(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 17:30:42 |
| Message-ID: | 20081215173042.GK4067@alvh.no-ip.org |
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| Lists: | pgsql-hackers |
Gregory Stark escribió:
> 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?
I guess it will be intolerably slow then. If we were to say "we have
CRC now, but if you enable it you have 1% of the performance" we will
get laughed at.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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