Re: No stats after promoting standby?

On Mon, Dec 4, 2017 at 4:02 PM, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
wrote:

> Those stats aren't part of regular data, so no they shouldn't.
>

I would consider object statistics to be part of a database, and a very
important part at that.

> The docs are telling half the truth when they say this is a
> not-bug-but-feature, though. It's true that we don't want to overwrite
> some of these counters, such as number of scans, number of tuples
> accessed, etc; but ideally we should keep things such as vacuum/analyze
> counts and last times, and also the counts of dead/live/
> mod_since_analyze tuples, to keep autovacuum informed without requiring
> an ANALYZE.
>

I'm not so worried about the time of last vacuum or analyze but the
statistics for optimizer usage would be necessary. Otherwise I would think
the time to complete a failover would have to include that "vacuumdb --all
--analyze-only" run as queries run before that could be very out-of-sorts
with no information on the data. Although perhaps I'm misunderstanding
where the optimizer gets its information from and these pg_stat_% tables
are not what I seem to think they are.

Anyway, sounds like you've all been over this one before. I'll just make a
note of it for my own reference for now.

Don.

--
Don Seiler
www.seiler.us