Re: Autovacuum on partitioned table (autoanalyze)

On Fri, Aug 20, 2021 at 07:55:13AM -0500, Justin Pryzby wrote:
> On Tue, Aug 17, 2021 at 06:30:18AM -0500, Justin Pryzby wrote:
> > On Mon, Aug 16, 2021 at 05:28:10PM -0500, Justin Pryzby wrote:
> > > On Mon, Aug 16, 2021 at 05:42:48PM -0400, Álvaro Herrera wrote:
> > > > On 2021-Aug-16, Álvaro Herrera wrote:
> > > >
> > > > > Here's the reversal patch for the 14 branch. (It applies cleanly to
> > > > > master, but the unused member of PgStat_StatTabEntry needs to be
> > > > > removed and catversion bumped).
> > > >
> > > > I have pushed this to both branches. (I did not remove the item from
> > > > the release notes in the 14 branch.)
> > >
> > > | I retained the addition of relkind 'p' to tables included by
> > > | pg_stat_user_tables, because reverting that would require a catversion
> > > | bump.
> > >
> > > Right now, on v15dev, it shows 0, which is misleading.
> > > Shouldn't it be null ?
> > >
> > > analyze_count | 0
> > >
> > > Note that having analyze_count and last_analyze would be an an independently
> > > useful change. Since parent tables aren't analyzed automatically, I have a
> > > script to periodically process them if they weren't processed recently. Right
> > > now, for partitioned tables, the best I could find is to check its partitions:
> > > | MIN(last_analyzed) FROM pg_stat_all_tables psat JOIN pg_inherits i ON psat.relid=i.inhrelid
> > >
> > > In 20200418050815(dot)GE26953(at)telsasoft(dot)com I wrote:
> > > |This patch includes partitioned tables in pg_stat_*_tables, which is great; I
> > > |complained awhile ago that they were missing [0]. It might be useful if that
> > > |part was split out into a separate 0001 patch (?).
> > > | [0] https://www.postgresql.org/message-id/20180601221428.GU5164%40telsasoft.com
> >
> > I suggest the attached (which partially reverts the revert), to allow showing
> > correct data for analyze_count and last_analyzed.
>
> Álvaro, would you comment on this ?
>
> To me this could be an open item, but someone else should make that
> determination.

I added an opened item until this is discussed.
| pg_stats includes partitioned tables, but always shows analyze_count=0
| Owner: Alvaro Herrera

Possible solutions, in decreasing order of my own preference:

- partially revert the revert, as proposed, to have "analyze_count" and
"last_analyzed" work properly for partitioned tables. This doesn't suffer
from any of the problems that led to the revert, does it ?

- Update the .c code to return analyze_count=NULL for partitioned tables.

- Update the catalog definition to exclude partitioned tables, again.
Requires a catalog bumped.

- Document that analyze_count=NULL for partitioned tables. It seems to just
document a misbehavior.

--
Justin