From: | Michael Paquier <michael(at)paquier(dot)xyz> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | Peter Eisentraut <peter(at)eisentraut(dot)org>, Jakub Wartak <jakub(dot)wartak(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com> |
Subject: | Re: pg_stat_get_activity(): integer overflow due to (int) * (int) for MemoryContextAllocHuge() |
Date: | 2023-09-27 22:53:45 |
Message-ID: | ZRSyefTyBOJi3Ydu@paquier.xyz |
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Lists: | pgsql-hackers |
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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