Re: BUG #16620: Autovacuum does not process certain databases after migration from postgresql 10

Problem gone after restarting the cluster.
Autovacuum started to process relations in other databases.

I dont know how to reproduce the issue, we will monitor it.
If there any way to debug it when it occurs again - let me know.

ср, 16 сент. 2020 г. в 16:40, PG Bug reporting form <noreply(at)postgresql(dot)org
>:

> The following bug has been logged on the website:
>
> Bug reference: 16620
> Logged by: Max Vikharev
> Email address: bm(dot)kinder(at)gmail(dot)com
> PostgreSQL version: 12.3
> Operating system: Linux
> Description:
>
> Hi,
>
> There is a cluster with 50 databases. The sizes of tables are very
> different, from megabytes to terabytes.
>
> We have been successfully used the aggressive autovacuum for a long time.
> After upgrade from 10 to 12.3 we've noticed that autovacuum always process
> relations from one database but does not reach others.
>
> I've used
>
> https://www.depesz.com/2020/01/29/which-tables-should-be-auto-vacuumed-or-auto-analyzed/comment-page-1/
> to detect existance of relations that should be autovacuumed. There are a
> lot of them. At the same time i see that there are free autovacuum workers
> that should do this work. But tables are not processed for a long time.
>
> I have logs (log_autovacuum_min_duration = 0) that confirms that only
> single
> database is constantly being autovacuumed. Within pg_stat_user_tables i see
> that last time autovacuum / autoanalyze for other databases happened in
> the
> same day when "vacuum to prevent wraparound" worked.
>
> Please help to investigate the problem. Why my relations does not processed
> and how can i fix it.
>
> Example table
> -[ RECORD 1 ]-------+------------------------------
> n_tup_ins | 25599733
> n_tup_upd | 2206685374
> n_tup_del | 19938580
> n_tup_hot_upd | 1863307770
> n_live_tup | 186473676
> n_dead_tup | 18177988
> n_mod_since_analyze | 3250337
> last_autovacuum | 2020-08-26 16:43:02.321971+03
> last_autoanalyze | 2020-08-26 14:04:19.132566+03
> vacuum_count | 1
> autovacuum_count | 4078
> analyze_count | 8
> autoanalyze_count | 357
>
> Autovacuum settings
> "autovacuum_max_workers" => 5,
> "autovacuum_naptime" => "30s",
> "autovacuum_vacuum_threshold" => 5000
> "autovacuum_vacuum_scale_factor" => 0.00001
> "autovacuum_vacuum_cost_delay" => "10ms"
> "autovacuum_vacuum_cost_limit" => 6000,
> "autovacuum_analyze_threshold" => 5000,
> "autovacuum_analyze_scale_factor" => "0.01"
>
>