Re: Statistics Import and Export

On Sat, 2024-03-30 at 01:34 -0400, Corey Huinker wrote:
>
> - 002pg_upgrade.pl now dumps before/after databases with --no-
> statistics. I tried to find out why some tables were getting their
> relstats either not set, or set and reset, never affecting the
> attribute stats. I even tried turning autovacuum off for both
> instances, but nothing seemed to change the fact that the same tables
> were having their relstats reset.

I think I found out why this is happening: a schema-only dump first
creates the table, then sets the relstats, then creates indexes. The
index creation updates the relstats, but because the dump was schema-
only, it overwrites the relstats with zeros.

That exposes an interesting dependency, which is that relstats must be
set after index creation, otherwise they will be lost -- at least in
the case of pg_upgrade.

This re-raises the question of whether stats are part of a schema-only
dump or not. Did we settle conclusively that they are?

Regards,
    Jeff Davis