Naming of the different stats systems / "stats collector"

Hi,

One thing I'm not yet happy around the shared memory stats patch is
naming. Currently a lot of comments say things like:

* [...] We convert to
* microseconds in PgStat_Counter format when transmitting to the collector.

or

# - Query and Index Statistics Collector -

or

/* ----------
* pgstat_report_subscription_drop() -
*
* Tell the collector about dropping the subscription.
* ----------
*/

the immediate question for the patch is what to replace "collector" with.

"stats subsystem" is too general, because that could be about
backend_activity.c, or pg_statistic, or ...

"shared memory stats" seems too focussed on the manner of storage, rather than
the kind of stats.

The patch currently uses "activity statistics" in a number of places, but that
is confusing too, because pg_stat_activity is a different kind of stats.

Any ideas?

The postgresql.conf.sample section header seems particularly odd - "index
statistics"? We collect more data about tables etc.

A more general point: Our naming around different types of stats is horribly
confused. We have stats describing the current state (e.g. pg_stat_activity,
pg_stat_replication, pg_stat_progress_*, ...) and accumulated stats
(pg_stat_user_tables, pg_stat_database, etc) in the same namespace. Should we
try to move towards something more coherent, at least going forward?

Greetings,

Andres Freund