Re: Add stats_reset to pg_stat_all_tables|indexes and related views

> while working on relfilenode statistics [1], I observed that it's possible to call
> pg_stat_reset_single_table_counters() on a relation but the reset time is not
> reported in the related views.
>
> I think it's interesting to know when the stats have been reset, so the attached
> patch is adding stats_reset to the related views.
>
> Also, it's more consistent with other stat kinds that also report reset times.

+1. This field should clearly be there.

> This new field is not included into the pg_stat_xact_* views because the 0 values
> in transaction-local stats have nothing to do with reset operations.
>
> The patch is pretty straightforward, it:

Nothing jumped out at me in the code. Although, I think we should add
at least one test where pg_stat_reset_single_table_counters() is called
with an index OID. There isn't a difference in the way the stats are
reset for indexes and tables, but they are presented in different views,
so it makes sense to add test coverage.

On a side note: I really think pg_stat_reset_single_table_counters is
the wrong name here, since other OIDs can be used here; indexes
or materialized views, etc. Maybe pg_stat_reset_single_relation_counters
will be better?

--
Sami Imseih
Amazon Web Services (AWS)