Re: Enabling Checksums

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
Cc: Simon Riggs <simon(at)2ndQuadrant(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Enabling Checksums
Date: 2013-03-13 06:33:04
Message-ID: 1363156384.29942.8.camel@jdavis-laptop
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On Thu, 2013-03-07 at 13:45 -0800, Jeff Davis wrote:
> I need to do another self-review after these changes and some more
> extensive testing, so I might have missed a couple things.

New patch attached.

Aside from rebasing, I also found a problem with temp tables. At first I
was going to fix it by continuing to exclude temp tables from checksums
entirely. But then I re-thought it and decided to just checksum temp
tables, too.

Excluding temp tables from checksums means more special cases in the
code, and more documentation. After thinking about it, there is no huge
benefit to excluding temp tables:
* small temp tables will be in memory only, and never checksummed
* no WAL for temp tables, so the biggest cost of checksums is
* there are good reasons to want to checksum temp tables, because they
can be used to stage data for permanent tables

However, I'm willing to be convinced to exclude temp tables again.

Jeff Davis

Attachment Content-Type Size
checksums-20130312.patch.gz application/x-gzip 22.0 KB
replace-tli-with-checksums-20130312.patch.gz application/x-gzip 8.9 KB

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