Re: BUG #16098: unexplained autovacuum to prevent wraparound

I can try reproducing it, I didn't quite get what is actually triggering
that. Let me share some more details:

Postgres instance is getting loaded of 4 big tables (not at the same time,
sequentially):

Table1: 2.5B rows
Table2: 2.2B rows
Table3: 7.7B rows
Table4: 1.3B rows

Autovacuum to prevent wrap around kicks in on those table, I was actually
wondering if this is somehow related to *autovacuum_multixact_freeze_max_age
*parameter and how. That behavior should be referred to row locking on
multiple transaction but this database is still static and not accessible
yet, meaning there shouldn't be row level concurrency. For completeness,
the load for each table is executed by 40 parallel sessions running the
copy command.

pgxxxxx=> show autovacuum_multixact_freeze_max_age;
autovacuum_multixact_freeze_max_age
-------------------------------------
400000000

Thanks
Alessandro

Il giorno ven 8 nov 2019 alle ore 16:12 Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
ha scritto:

> On Thu, Nov 7, 2019 at 12:11 PM Alessandro Ferraresi <
> alessandro(dot)ferraresi1(at)gmail(dot)com> wrote:
>
>>
>> Here you go:
>>
>> pgxxxxx=> show vacuum_freeze_table_age;
>> vacuum_freeze_table_age
>> -------------------------
>> 150000000
>>
>
> I can't think of any other innocent explanations, so maybe it is a bug.
> But if it were easy to hit, I'd expect it to have been noticed before now.
>
> Can you reproduce it readily?
>
> Cheers,
>
> Jeff
>
>>