| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Avoiding unnecessary reads in recovery |
| Date: | 2007-04-27 13:16:42 |
| Message-ID: | 20070427131642.GD4645@alvh.no-ip.org |
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| Lists: | pgsql-hackers |
Heikki Linnakangas wrote:
> What we could have is the semantics of "Return a buffer, with either
> correct contents or completely zeroed out". It would act just like
> ReadBuffer if the buffer was already in memory, and zero out the page
> otherwise. That's a bit strange semantics to have, but is simple to
> implement and works for the use-cases we've been talking about.
Huh, why does that work in the case where the recovery code reads a
page, then evicts it because of memory pressure, and later needs to read
it again?
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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