| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndQuadrant(dot)com>, Ants Aasma <ants(at)cybertec(dot)at>, Greg Smith <greg(at)2ndquadrant(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Enabling Checksums |
| Date: | 2013-04-12 19:21:46 |
| Message-ID: | 20130412192146.GD28226@momjian.us |
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| Lists: | pgsql-hackers |
On Fri, Apr 12, 2013 at 12:07:36PM -0700, Jeff Davis wrote:
> > (Attached patch is discussion only. Checking checksum in recovery
> > isn't coded at all.)
>
> I like it.
>
> A few points:
>
> * Given that setting the checksum is unconditional in a backup block, do
> we want to zero the checksum field when the backup block is restored if
> checksums are disabled? Otherwise we would have a strange situation
> where some blocks have a checksum on disk even when checksums are
> disabled.
>
> * When we do PageSetChecksumInplace(), we need to be 100% sure that the
> hole is empty; otherwise the checksum will fail when we re-expand it. It
> might be worth a memset beforehand just to be sure.
Do we write the page holes to the WAL for full-page writes? I hope we
don't.
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
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