Re: Enabling Checksums
Simon Riggs <simon@2ndquadrant.com>
From: Simon Riggs <simon@2ndQuadrant.com>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Heikki Linnakangas <hlinnakangas@vmware.com>, Greg Smith <greg@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2013-03-17T20:45:31Z
Lists: pgsql-hackers
On 13 March 2013 06:33, Jeff Davis <pgsql@j-davis.com> wrote: > 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 > non-existent > * 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. I'm convinced we must include temp tables. No point putting a lock on the front door if there's a back door still open. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services