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help / color / mirror / Atom feedFrom: Michael Paquier <[email protected]>
To: Andres Freund <[email protected]>
Cc: Peter Eisentraut <[email protected]>
Cc: Jakub Wartak <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: Robert Haas <[email protected]>
Subject: Re: pg_stat_get_activity(): integer overflow due to (int) * (int) for MemoryContextAllocHuge()
Date: Thu, 28 Sep 2023 07:53:45 +0900
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CAKZiRmw8QSNVw2qNK-dznsatQqz+9DkCquxP0GHbbv1jMkGHMA@mail.gmail.com>
<[email protected]>
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On Wed, Sep 27, 2023 at 10:29:25AM -0700, Andres Freund wrote:
> I don't think going for size_t is a viable path for fixing this. I'm pretty
> sure the initial patch would trigger a type mismatch from guc_tables.c - we
> don't have infrastructure for size_t GUCs.
Nothing marked as PGDLLIMPORT uses size_t in the tree currently, FWIW.
> Perhaps we ought to error out (in BackendStatusShmemSize() or such) if
> pgstat_track_activity_query_size * MaxBackends >= 4GB?
Yeah, agreed that putting a check like that could catch errors more
quickly.
> Frankly, it seems like a quite bad idea to have such a high limit for
> pgstat_track_activity_query_size. The overhead such a high value has will
> surprise people...
Still it could have some value for some users with large analytical
queries where the syslogger is not going to be a bottleneck? It seems
too late to me to change that, but perhaps the docs could be improved
to tell that using a too high value can have performance consequences,
while mentioning the maximum value.
--
Michael
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Subject: Re: pg_stat_get_activity(): integer overflow due to (int) * (int) for MemoryContextAllocHuge()
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