Re: ANALYZE ONLY

On Sun, Sep 22, 2024 at 9:09 PM David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
>
> v7-0002 is all my changes.
>
> I'd like to push this soon, so if anyone has any last-minute feedback,
> please let me know in the next few days.
>

drop table if exists only_inh_parent,only_inh_child;
CREATE TABLE only_inh_parent (a int , b INT) with (autovacuum_enabled = false);
CREATE TABLE only_inh_child () INHERITS (only_inh_parent) with
(autovacuum_enabled = false);
INSERT INTO only_inh_child(a,b) select g % 80, (g + 1) % 200 from
generate_series(1,1000) g;
select pg_table_size('only_inh_parent');
ANALYZE ONLY only_inh_parent;

select stadistinct,starelid::regclass,staattnum, stainherit
from pg_statistic
where starelid = ANY ('{only_inh_parent, only_inh_child}'::regclass[]);

stadistinct | starelid | staattnum | stainherit
-------------+-----------------+-----------+------------
80 | only_inh_parent | 1 | t
-0.2 | only_inh_parent | 2 | t

---------------
catalog-pg-statistic.html
stainherit bool
If true, the stats include values from child tables, not just the
values in the specified relation

Normally there is one entry, with stainherit = false, for each table
column that has been analyzed. If the table has inheritance children
or partitions, a second entry with stainherit = true is also created.
This row represents the column's statistics over the inheritance tree,
i.e., statistics for the data you'd see with SELECT column FROM
table*, whereas the stainherit = false row represents the results of
SELECT column FROM ONLY table.

I do understand what Michael Harris said in [1]
---------------

Given the above context, I am still confused with this sentence in
sql-analyze.html.
"If ONLY is specified before the table name, only that table is analyzed."

like in the above sql example, only_inh_parent's child is also being analyzed.

[1] https://www.postgresql.org/message-id/CADofcAW43AD%3Dqqtj1cLkTyRpPM6JB5ZALUK7CA1KZZqpcouoYw%40mail.gmail.com