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help / color / mirror / Atom feedFrom: Tom Lane <[email protected]>
To: Melanie Plageman <[email protected]>
Cc: Greg Stark <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Kyotaro Horiguchi <[email protected]>
Cc: Justin Pryzby <[email protected]>
Cc: Thomas Munro <[email protected]>
Cc: David G. Johnston <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: shared-memory based stats collector - v70
Date: Wed, 20 Jul 2022 12:08:35 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAAKRu_Z18jYbarKA4GZMOO00KtUqKtBqgQ8SgB=wSvSqKq3iiA@mail.gmail.com>
References: <[email protected]>
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Melanie Plageman <[email protected]> writes:
> On Wed, Jul 20, 2022 at 11:35 AM Greg Stark <[email protected]> wrote:
>> It seems like if we really think the total number of database objects
>> is reasonably limited to scales that fit in RAM there would be a much
>> simpler database design that would just store the catalog tables in
>> simple in-memory data structures and map them all on startup without
>> doing all the work Postgres does to make relational storage scale.
> I think efforts to do such a thing have gotten caught up in solving
> issues around visibility and managing the relationship between local and
> global caches [1]. It doesn't seem like the primary technical concern
> was memory usage.
AFAIR, the previous stats collector implementation had no such provision
either: it'd just keep adding hashtable entries as it received info about
new objects. The only thing that's changed is that now those entries are
in shared memory instead of process-local memory. We'd be well advised to
be sure that memory can be swapped out under pressure, but otherwise I'm
not seeing that things have gotten worse.
regards, tom lane
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Subject: Re: shared-memory based stats collector - v70
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