Re: progress report for ANALYZE

Yamada-san,

On Fri, Nov 29, 2019 at 5:45 PM Tatsuro Yamada
<tatsuro(dot)yamada(dot)tf(at)nttcom(dot)co(dot)jp> wrote:
> Attached patch is the revised patch. :)
>
> I wonder two things below. What do you think?
>
> 1)
> For now, I'm not sure it should be set current_child_table_relid to zero
> when the current phase is changed from "acquiring inherited sample rows" to
> "computing stats". See <Test result> bellow.

In the upthread discussion [1], Robert asked to *not* do such things,
that is, resetting some values due to phase change. I'm not sure his
point applies to this case too though.

> 2)
> There are many "finalizing analyze" phases based on relids in the case
> of partitioning tables. Would it better to fix the document? or it
> would be better to reduce it to one?
>
> <Document>
> ---------------------------------------------------------
> <entry><literal>finalizing analyze</literal></entry>
> <entry>
> The command is updating pg_class. When this phase is completed,
> <command>ANALYZE</command> will end.
> ---------------------------------------------------------

When a partitioned table is analyzed, its partitions are analyzed too.
So, the ANALYZE command effectively runs N + 1 times if there are N
partitions -- first analyze partitioned table to collect "inherited"
statistics by collecting row samples using
acquire_inherited_sample_rows(), then each partition to collect its
own statistics. Note that this recursive application to ANALYZE to
partitions (child tables) only occurs for partitioned tables, not for
legacy inheritance.

Thanks,
Amit