| From: | Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru> |
|---|---|
| To: | Michael Paquier <michael(at)paquier(dot)xyz>, Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | David Steele <david(at)pgmasters(dot)net>, Magnus Hagander <magnus(at)hagander(dot)net>, Michael Banck <michael(dot)banck(at)credativ(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Asif Rehman <asifr(dot)rehman(at)gmail(dot)com>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Online verification of checksums |
| Date: | 2020-11-23 12:53:42 |
| Message-ID: | 196553ba-65ac-ce1b-acd9-24209d9ec9eb@postgrespro.ru |
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| Lists: | pgsql-hackers |
On 21.11.2020 04:30, Michael Paquier wrote:
> The only method I can think as being really
> reliable is based on two facts:
> - Do a check only on pd_checksums, as that validates the full contents
> of the page.
> - When doing a retry, make sure that there is no concurrent I/O
> activity in the shared buffers. This requires an API we don't have
> yet.
It seems reasonable to me to rely on checksums only.
As for retry, I think that API for concurrent I/O will be complicated.
Instead, we can introduce a function to read the page directly from
shared buffers after PAGE_RETRY_THRESHOLD attempts. It looks like a
bullet-proof solution to me. Do you see any possible problems with it?
--
Anastasia Lubennikova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
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