Horton

Re: Berserk Autovacuum (let's save next Mandrill)

Laurenz Albe <laurenz.albe@cybertec.at>

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From: Laurenz Albe <laurenz.albe@cybertec.at>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Alexander Korotkov <a.korotkov@postgrespro.ru>, Justin Pryzby <pryzby@telsasoft.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Masahiko Sawada <masahiko.sawada@2ndquadrant.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Darafei Komяpa Praliaskouski <me@komzpa.net>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Michael Banck <mbanck@gmx.net>
Date: 2020-03-28T04:12:11Z
Lists: pgsql-hackers 
On Sat, 2020-03-28 at 11:59 +1300, David Rowley wrote:
> On Fri, 27 Mar 2020 at 22:40, Laurenz Albe <laurenz.albe@cybertec.at> wrote:
> > The new meaning of -2 should be documented, other than that it looks
> > good to me.
> 
> But the users don't need to know anything about -2. It's not possible
> to explicitly set the value to -2. This is just the reset value of the
> reloption which means "use the GUC".

I see.

> > I'll accept the new semantics, but they don't make me happy.  People are
> > used to -1 meaning "use the GUC value instead".
> 
> The problem with having -1 on the reloption meaning use the GUC, in
> this case, is that it means the reset value of the reloption must be
> -1 and we need to allow them to set -2 explicitly, and if we do that,
> then -1 also becomes a valid value that users can set. Maybe that's
> not the end of the world, but I'd rather have the reset value be
> unsettable by users. To me, that's less confusing as there are fewer
> special values to remember the meaning of.
> 
> The reason I want a method to explicitly disable the feature is the
> fact that it's easy to document and it should reduce the number of
> people who are confused about the best method to disable the feature.
> I know there's going to be a non-zero number of people who'll want to
> do that.

In the light of that, I have no objections.

Yours,
Laurenz Albe

Commits

  1. Further improve stability fix for partition_aggregate test.

  2. Improve stability fix for partition_aggregate test.

  3. Attempt to stabilize partitionwise_aggregate test

  4. Fix race condition in statext_store().

  5. Attempt to fix unstable regression tests, take 2

  6. Attempt to fix unstable regression tests

  7. Trigger autovacuum based on number of INSERTs

  8. Fix upper limit for vacuum_cleanup_index_scale_factor