Re: Add tracking of backend memory allocated to pg_stat_activity

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