On Mon, Sep 23, 2024 at 6:04 PM David Rowley <dgrowleyml@gmail.com> wrote:
>
>
> If this is confusing, I think there's a bunch of detail that I tried
> to keep that's just not that useful. The part about analyzing
> partitions just once and the part about not collecting non-inheritance
> stats for the partitioned table seems like extra detail that's either
> obvious or just not that important.
>
> Can you have a look at the attached and let me know if it's easier to
> understand now?
>
Now the regress test passed.
<para>
For partitioned tables, <command>ANALYZE</command> gathers statistics by
sampling rows from all partitions. By default,
<command>ANALYZE</command> will also recursively collect and update the
statistics for each partition. The <literal>ONLY</literal> keyword may be
used to disable this.
</para>
is very clear to me!
<para>
If the table being analyzed has inheritance children,
<command>ANALYZE</command> gathers two sets of statistics: one on the rows
of the parent table only, and a second including rows of both the parent
table and all of its children. This second set of statistics is needed when
planning queries that process the inheritance tree as a whole. The
autovacuum daemon, however, will only consider inserts or updates on the
parent table itself when deciding whether to trigger an automatic analyze
for that table. If that table is rarely inserted into or updated, the
inheritance statistics will not be up to date unless you run
<command>ANALYZE</command> manually. By default,
<command>ANALYZE</command> will also recursively collect and update the
statistics for each inheritance child table. The <literal>ONLY</literal>
keyword may be used to disable this.
</para>
looks fine. but maybe we can add the following information
"if The <literal>ONLY</literal> is specified, the second set of
statistics won't include each children individual statistics"
I think that's the main difference between specifying ONLY or not?
catalog-pg-statistic.html second paragraph seems very clear to me.
Maybe we can link it somehow
Other than that, it looks good to me.
