Message-ID: <8088ebdf-247d-4014-b6f9-a1d800aabded@oss.nttdata.com>
Date: Thu, 11 Jul 2024 01:07:51 +0900
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Subject: Re: Add a GUC check hook to ensure summarize_wal cannot be enabled
 when wal_level is minimal
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To: Nathan Bossart <nathandbossart@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Jelte Fennema-Nio <postgres@jeltef.nl>,
 Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@lists.postgresql.org
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From: Fujii Masao <masao.fujii@oss.nttdata.com>
In-Reply-To: <Zo6sTje4m0czRor9@nathan>
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On 2024/07/11 0:44, Nathan Bossart wrote:
> On Wed, Jul 10, 2024 at 11:11:13AM -0400, Tom Lane wrote:
>> Please, no.  We went through a ton of permutations of that kind of
>> idea years ago, when it first became totally clear that cross-checks
>> between GUCs do not work nicely if implemented in check_hooks.
>> (You can find all the things we tried in the commit log, although
>> I don't recall exactly when.)
> 
> Understood.
> 
>> A counter-example for what you just
>> said is when a configuration file like the above is loaded after
>> postmaster start.
> 
> I haven't tested it, but from skimming around the code, it looks like
> ProcessConfigFileInternal() would deduplicate any previous entries in the
> file prior to applying the values and running the check hooks.  Else,
> reloading a configuration file with multiple startup-only GUC entries could
> fail, even without bogus GUC check hooks.

Yeah, I'm thinking the same.

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION