Re: BUG #17928: Standby fails to decode WAL on termination of primary

From: Alexander Lakhin <exclusion(at)gmail(dot)com>
To: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Sergei Kornilov <sk(at)zsrv(dot)org>, Noah Misch <noah(at)leadboat(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, pgsql-bugs(at)lists(dot)postgresql(dot)org, Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>
Subject: Re: BUG #17928: Standby fails to decode WAL on termination of primary
Date: 2023-09-19 13:00:06
Message-ID: ee604ee6-f464-1502-0289-f1046c85c182@gmail.com
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19.09.2023 13:09, Thomas Munro wrote:
> On Tue, Sep 19, 2023 at 9:53 PM Michael Paquier<michael(at)paquier(dot)xyz> wrote:
>> On Tue, Sep 19, 2023 at 09:25:34PM +1200, Thomas Munro wrote:
>>> The problem was that the Perl functions advance_XXX() would sometimes
>>> see an "unflushed" insert position caused by hint records and other
>>> incidental stuff, and then we'd write our contrived header at a
>>> disconnected location after a bunch of (unwritten) zeroes. The
>>> solution in this version is to start each test with
>>> emit_message($node, 0), which flushes a small record.
>>>

Thanks for the fixes!

I've tested this patch version on Debian 9 and it works fine now.
But as to wal_log_hints, I see that v7 patches work for REL_12_STABLE and
REL_13_STABLE, but not for other branches, though v6 patches definitely
failed on REL_12_STABLE and REL_13_STABLE too. So the behavior improved,
but not for all versions, for some reason (I haven't looked deeper yet).
Also I've noticed a few minor discrepancies in the patches.
A commit message in patch.15 contains the sentence "We should fix ...",
not "We could fix ...", as in commit messages for other versions.
Also, patch.12 contains a duplicated "Reviewed-by" string.
And may be "xlp_prev" is a typo?

Best regards,
Alexander

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