Re: [patch] Fix checksum verification in base backups for zero page headers

From: Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Michael Banck <michael(dot)banck(at)credativ(dot)de>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [patch] Fix checksum verification in base backups for zero page headers
Date: 2020-10-27 19:56:23
Message-ID: ce25a60e-bd70-6554-1e8f-7e4dc9f6ce59@postgrespro.ru
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On 26.10.2020 04:13, Michael Paquier wrote:
> On Fri, Oct 23, 2020 at 08:00:08AM +0900, Michael Paquier wrote:
>> Yeah, we could try to make the logic a bit more complicated like
>> that. However, for any code path relying on a page read without any
>> locking insurance, we cannot really have a lot of trust in any of the
>> fields assigned to the page as this could just be random corruption
>> garbage, and the only thing I am ready to trust here a checksum
>> mismatch check, because that's the only field on the page that's
>> linked to its full contents on the 8k page. This also keeps the code
>> simpler.
> A small update here. I have extracted the refactored part for
> PageIsVerified() and committed it as that's independently useful.
> This makes the patch proposed here simpler on HEAD, leading to the
> attached.
> --
> Michael

Thank you for committing the first part.

In case you need a second opinion on the remaining patch, it still looks
good to me.

--
Anastasia Lubennikova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

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