Date: Wed, 6 Apr 2022 14:34:19 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Andres Freund <andres@anarazel.de>
Cc: Lukas Fittl <lukas@fittl.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	melanieplageman@gmail.com, Thomas Munro <thomas.munro@gmail.com>,
	"David G. Johnston" <david.g.johnston@gmail.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: shared-memory based stats collector - v70
Message-ID: <20220406193419.GA24419@telsasoft.com>
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On Wed, Apr 06, 2022 at 12:27:34PM -0700, Andres Freund wrote:
> > > +   next use of statistical information will cause a new snapshot to be built
> > > +   or accessed statistics to be cached.
> > 
> > I believe this should be an "and", not an "or". (next access builds both a
> > new snapshot and caches accessed statistics)
> 
> I *think* or is correct? The new snapshot is when stats_fetch_consistency =
> snapshot, the cached is when stats_fetch_consistency = cache. Not sure how to
> make that clearer without making it a lot longer. Suggestions?

I think it's correct.  Maybe it's clearer to say:

+   next use of statistical information will (when in snapshot mode) cause a new snapshot to be built
+   or (when in cache mode) accessed statistics to be cached.