Re: Possible corruption by CreateRestartPoint at promotion

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Nathan Bossart <nathandbossart(at)gmail(dot)com>
Cc: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org, masao(dot)fujii(at)oss(dot)nttdata(dot)com
Subject: Re: Possible corruption by CreateRestartPoint at promotion
Date: 2022-04-28 00:12:13
Message-ID: Ymnb3XlT4YwJ5yOH@paquier.xyz
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On Wed, Apr 27, 2022 at 11:09:45AM -0700, Nathan Bossart wrote:
> On Wed, Apr 27, 2022 at 02:16:01PM +0900, Michael Paquier wrote:
>> - if (ControlFile->state == DB_IN_ARCHIVE_RECOVERY &&
>> - ControlFile->checkPointCopy.redo < lastCheckPoint.redo)
>> - {
>> 7ff23c6 has removed the last call to CreateCheckpoint() outside the
>> checkpointer, meaning that there is one less concurrent race to worry
>> about, but I have to admit that this change, to update the control
>> file's checkPoint and checkPointCopy even if we don't check after
>> ControlFile->checkPointCopy.redo < lastCheckPoint.redo would make the
>> code less robust in ~14. So I am questioning whether a backpatch
>> is actually worth the risk here.
>
> IMO we should still check this before updating ControlFile to be safe.

Sure. Fine by me to play it safe.
--
Michael

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