| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Corey Huinker <corey(dot)huinker(at)gmail(dot)com> |
| Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
| Subject: | Re: Statistics Import and Export |
| Date: | 2024-04-01 17:06:45 |
| Message-ID: | 57e2d0c87d30e9b0dfb80f5b5d6a1a82a2539f10.camel@j-davis.com |
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| Lists: | pgsql-hackers |
On Sat, 2024-03-30 at 20:08 -0400, Tom Lane wrote:
> I haven't looked at the details, but I'm really a bit surprised
> by Jeff's assertion that CREATE INDEX destroys statistics on the
> base table. That seems wrong from here, and maybe something we
> could have it not do. (I do realize that it recalculates reltuples
> and relpages, but so what? If it updates those, the results should
> be perfectly accurate.)
In the v15 of the patch I was looking at, "pg_dump -s" included the
statistics. The stats appeared first in the dump, followed by the
CREATE INDEX commands. The latter overwrote the relpages/reltuples set
by the former.
While zeros are the right answers for a schema-only dump, it defeated
the purpose of including relpages/reltuples stats in the dump, and
caused the pg_upgrade TAP test to fail.
You're right that there are a number of ways this could be resolved --
I don't think it's an inherent problem.
Regards,
Jeff Davis
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