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From: Drouvot, Bertrand <[email protected]>
To: Justin Pryzby <[email protected]>
To: Stephen Frost <[email protected]>
Cc: Kyotaro Horiguchi <[email protected]>
Cc: [email protected]
Cc: [email protected]
Subject: Re: Add tracking of backend memory allocated to pg_stat_activity
Date: Mon, 12 Sep 2022 09:59:15 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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Hi,

On 9/9/22 7:08 PM, Justin Pryzby wrote:
> On Fri, Sep 09, 2022 at 12:34:15PM -0400, Stephen Frost wrote:
>>> While we are at it, what do you think about also recording the max memory
>>> allocated by a backend? (could be useful and would avoid sampling for which
>>> there is no guarantee to sample the max anyway).
>> What would you do with that information..?  By itself, it doesn't strike
>> me as useful.  Perhaps it'd be interesting to grab the max required for
>> a particular query in pg_stat_statements or such but again, that's a
>> very different thing.
>
> Storing the maxrss per backend somewhere would be useful (and avoid the
> issue of "sampling" with top), after I agree that it ought to be exposed
> to a view.  For example, it might help to determine whether (and which!)
> backends are using large multiple of work_mem, and then whether that can
> be increased.  If/when we had a "memory budget allocator", this would
> help to determine how to set its GUCs, maybe to see "which backends are
> using the work_mem that are precluding this other backend from using
> efficient query plan".

+1.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services:https://aws.amazon.com

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