Re: Statistics Import and Export

On Tue, Jan 21, 2025 at 7:31 AM Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
>
> On Mon, 2025-01-20 at 16:45 -0500, Corey Huinker wrote:
> >
> > What I struggle to understand is how that purpose isn't served better
> > by statistics being in SECTION_NONE like COMMENTs are, so that they
> > are imported immediately after the object that they reference.
>
> Tom, you expressed the strongest opinions on this point, can you expand
> a bit?
>
> If I understand correctly:
>
> * We strongly want stats to be exported by default[1].
>
> * Adding a SECTION_STATS could work, but would be non-trivial and might
> break expectations about the set of sections available[2].
>
> * SECTION_NONE doesn't seem right. There would be no way to get the
> stats using --section. Also, if there is no section boundary for the
> stats, then couldn't they appear in a surprising order?
>
> * I'm not sure about placing stats in SECTION_POST_DATA. That doesn't
> seem terrible to me, but not great either.
>

index is on SECTION_POST_DATA.
To dump all the statistics, we have to go through SECTION_POST_DATA.
place it there would be more convenient.

Tomas Vondra also mentioned this on [1]
[1] https://www.postgresql.org/message-id/bf724b21-914a-4497-84e3-49944f9776f6%40enterprisedb.com

> * I'm also not 100% sure about the flags. The default should dump the
> stats, of course. And I like the idea of allowing any combination of
> schema, data and stats to be exported. But that leaves a wrinkle for --
> data-only, which (as of v38) does not dump stats, because stats are a
> third kind of thing. Perhaps stats should be expressed as a subtype of
> data somehow, but I'm not sure exactly how.
>
if we have --data-only, --schema-only, --statistics-only, three options, then
--data-only also dump statistics would be unintuitive?