Re: How can i be certain autovacuum is causing reuse if table still grows

On Wed, Aug 5, 2020 at 9:29 AM MichaelDBA <MichaelDBA(at)sqlexec(dot)com> wrote:

> Hi Keith,
>
> I think statistics are also reset and not persistent through restarts when
> the pg_ctl option "-m immediate" is used when shutting down PG since it
> forces recovery mode when starting PG back up. By the way, for PostgreSQL
> Aurora, statistics are reset automatically every time aurora forces PG to
> restart or reboot or the user selects that option manually. I reported
> this as a bug with Aurora a few months ago. They said it was not a bug,
> but a feature that the might implement in the future. YUK.
>
> Regards,
> Michael Vitale
>
>

An "immediate" shutdown is often considered a crash to Postgres. So yes, it
likely will reset the statistics.

>
> Keith Fiske wrote on 8/4/2020 6:25 PM:
>
>
>
> On Tue, Aug 4, 2020 at 3:54 PM Scott Ribe <scott_ribe(at)elevated-dev(dot)com>
> wrote:
>
>> > On Aug 4, 2020, at 12:31 PM, Sidney Aloisio Ferreira Pryor <
>> sidney(at)tjrj(dot)jus(dot)br> wrote:
>> >
>> > Beside this, i saw on pg_stat_tables and the vacuum and autovacuum
>> count for this table is 0.
>>
>> Those values are not persistent; they are only since the last start of PG.
>>
>>
> This is not correct. Statistics are persistent through restarts. They are
> only reset during specific cases such as a crash or a major version
> upgrade. They can also be reset at any time manually.
>
> --
> Keith Fiske
> Senior Database Engineer
> Crunchy Data - http://crunchydata.com
>
>
>

--
Keith Fiske
Senior Database Engineer
Crunchy Data - http://crunchydata.com