From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
---|---|
To: | Stephen Frost <sfrost(at)snowman(dot)net> |
Cc: | Aidan Van Dyk <aidan(at)highrise(dot)ca>, Josh Berkus <josh(at)agliodbs(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Page Checksums |
Date: | 2011-12-19 14:33:22 |
Message-ID: | 1324305084-sup-6213@alvh.no-ip.org |
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Lists: | pgsql-hackers |
Excerpts from Stephen Frost's message of lun dic 19 11:18:21 -0300 2011:
> * Aidan Van Dyk (aidan(at)highrise(dot)ca) wrote:
> > #) Anybody investigated putting the CRC in a relation fork, but not
> > right in the data block? If the CRC contains a timestamp, and is WAL
> > logged before the write, at least on reading a block with a wrong
> > checksum, if a warning is emitted, the timestamp could be looked at by
> > whoever is reading the warning and know tht the block was written
> > shortly before the crash $X $PERIODS ago....
>
> I do like the idea of putting the CRC info in a relation fork, if it can
> be made to work decently, as we might be able to then support it on a
> per-relation basis, and maybe even avoid the on-disk format change..
>
> Of course, I'm sure there's all kinds of problems with that approach,
> but it might be worth some thinking about.
I think the main objection to that idea was that if you lose a single
page of CRCs you have hundreds of data pages which no longer have good
CRCs.
--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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