Re: REVIEW: Track TRUNCATE via pgstat

Alvaro Herrera <alvherre@2ndquadrant.com> writes:
>> 
>> Another idea would be exposing pgstat_report_stat(true) at SQL level.
>> That would eleminate the need for explicit pg_sleep(>=0.5), but we'll
>> still need the wait_for_... call to make sure the collector has picked
>> it up.
>
> We already have a stats test that sleeps.  Why not add this stuff there,
> to avoid making another test slow?

Well, if we could come up with a set of statements to test that would
produce the end result unambigously, so that we can be certain the stats
we check at the end cannot be a result of neat interaction of buggy
behavior...

I'm not sure this is at all possible, but I know for sure it will make
debugging the possible fails harder.  Even with the current approach of
checking the stats after every isolated case it's sometimes takes quite
a little more than a glance to verify correctness due to side-effects of
rollback (ins/upd/del counters are still updated), and the way stats are
affecting the dead tuples counter.

I'll try to see if the checks can be converged though.

--
Alex