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Re: Enabling Checksums

Jim Nasby <jim@nasby.net>

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From: Jim Nasby <jim@nasby.net>
To: Simon Riggs <simon@2ndQuadrant.com>
Cc: Jeff Davis <pgsql@j-davis.com>, Daniel Farina <daniel@heroku.com>, Greg Smith <greg@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@2ndquadrant.com>, Ants Aasma <ants@cybertec.at>, Heikki Linnakangas <hlinnakangas@vmware.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2013-03-23T04:26:27Z
Lists: pgsql-hackers 
On 3/18/13 2:25 PM, Simon Riggs wrote:
> On 18 March 2013 19:02, Jeff Davis <pgsql@j-davis.com> wrote:
>> On Sun, 2013-03-17 at 22:26 -0700, Daniel Farina wrote:
>>> as long as I am able to turn them off easily
>>
>> To be clear: you don't get the performance back by doing
>> "ignore_checksum_failure = on". You only get around the error itself,
>> which allows you to dump/reload the good data.
>
> Given that the worst pain point comes from setting hint bits during a
> large SELECT, it makes sense to offer an option to simply skip hint
> bit setting when we are reading data (SELECT, not
> INSERT/UPDATE/DELETE). That seems like a useful option even without
> checksums. I know I have seen cases across many releases where setting
> that would have been good, since it puts the cleanup back onto
> VACUUM/writers, rather than occasional SELECTs.

+1