Re: Autovacuum and visibility maps

On Tue, Dec 3, 2024 at 11:57 AM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:
[snip]

>
> I have to believe it is due to this:
>
>
> https://www.postgresql.org/docs/current/routine-vacuuming.html#VACUUM-FOR-SPACE-RECOVERY
>
> "If you have a table whose entire contents are deleted on a periodic
> basis, consider doing it with TRUNCATE rather than using DELETE followed
> by VACUUM. TRUNCATE removes the entire content of the table immediately,
> without requiring a subsequent VACUUM or VACUUM FULL to reclaim the
> now-unused disk space. The disadvantage is that strict MVCC semantics
> are violated."
>
> Combined with this:
>
>
> https://www.postgresql.org/docs/current/runtime-config-autovacuum.html#GUC-AUTOVACUUM-VACUUM-INSERT-THRESHOLD
>
> "autovacuum_vacuum_threshold
>
> Specifies the minimum number of updated or deleted tuples needed to
> trigger a VACUUM in any one table. ...
>
> "
>
> I'm going to say the TRUNCATE itself does not trigger an autovacuum. I
> would suggest throwing a manual VACUUM in the table population script.
>

Shouldn't autovacuum_vacuum_insert_threshold kick off an autovacuum if
you're doing a lot of inserts?

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