Horton

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

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Andres Freund <andres@anarazel.de>, Masahiko Sawada <masahiko.sawada@2ndquadrant.com>, David Rowley <dgrowleyml@gmail.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>, pgsql-hackers@lists.postgresql.org, Alvaro Herrera <alvherre@2ndquadrant.com>, Michael Banck <mbanck@gmx.net>
Date: 2020-03-17T21:34:26Z
Lists: pgsql-hackers 
On Tue, Mar 17, 2020 at 10:22:44PM +0100, Laurenz Albe wrote:
> On Tue, 2020-03-17 at 16:07 -0500, Justin Pryzby wrote:
> > > Assume a scale factor >= 1, for example 2, and n live tuples.
> > > The table has just been vacuumed.
> > > 
> > > Now we insert m number tuples (which are live).

.. but not yet counted in reltuples.

On Tue, Mar 17, 2020 at 10:22:44PM +0100, Laurenz Albe wrote:
> Note that this is different from autovacuum_vacuum_scale_factor,
> because inserted tuples are live, while dead tuples are not.

But they're not counted in reltuples until after the next vacuum (or analyze),
which is circular, since it's exactly what we're trying to schedule.

                reltuples = classForm->reltuples;
                vactuples = tabentry->n_dead_tuples;
+               instuples = tabentry->inserts_since_vacuum;
                anltuples = tabentry->changes_since_analyze;
 
                vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples;
+               vacinsthresh = (float4) vac_ins_base_thresh + vac_ins_scale_factor * reltuples;

-- 
Justin

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