From: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
---|---|
To: | Andrei Zubkov <zubkov(at)moonset(dot)ru> |
Cc: | Alena Rybakina <lena(dot)ribackina(at)yandex(dot)ru>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru> |
Subject: | Re: Vacuum statistics |
Date: | 2024-06-27 01:39:45 |
Message-ID: | CAD21AoDQ3bc+ebbhMvDy9eZ=QBnN-mHTAc0569cbnWXjozx0dw@mail.gmail.com |
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On Fri, May 31, 2024 at 4:19 AM Andrei Zubkov <zubkov(at)moonset(dot)ru> wrote:
>
> Hi,
>
> Th, 30/05/2024 at 10:33 -0700, Alena Rybakina wrote:
> > I suggest gathering information about vacuum resource consumption for
> > processing indexes and tables and storing it in the table and index
> > relationships (for example, PgStat_StatTabEntry structure like it has
> > realized for usual statistics). It will allow us to determine how
> > well
> > the vacuum is configured and evaluate the effect of overhead on the
> > system at the strategic level, the vacuum has gathered this
> > information
> > already, but this valuable information doesn't store it.
> >
> It seems a little bit unclear to me, so let me explain a little the
> point of a proposition.
>
> As the vacuum process is a backend it has a workload instrumentation.
> We have all the basic counters available such as a number of blocks
> read, hit and written, time spent on I/O, WAL stats and so on.. Also,
> we can easily get some statistics specific to vacuum activity i.e.
> number of tuples removed, number of blocks removed, number of VM marks
> set and, of course the most important metric - time spent on vacuum
> operation.
I've not reviewed the patch closely but it sounds helpful for users. I
would like to add a statistic, the high-water mark of memory usage of
dead tuple TIDs. Since the amount of memory used by TidStore is hard
to predict, I think showing the high-water mark would help users to
predict how much memory they set to maintenance_work_mem.
Regards,
--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com
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