Re: Add min and max execute statement time in pg_stat_statement

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Mon, Apr 7, 2014 at 4:19 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
>>> What it does is add a new function pg_stat_statements_reset_time() which
>>> resets the min and max values from all function's entries, without
>>> touching the stddev state variables nor the number of calls. Note
>>> there's no ability to reset the values for a single function.

>> That seems pretty bizarre. At this late date, the best thing would
>> probably be to strip out the undiscussed functionality. It can get
>> resubmitted for 9.5 if there's a real use-case for it.

> If I'm understanding correctly, that actually seems reasonably
> sensible. I mean, the big problem with min/max is that you might be
> taking averages and standard deviations over a period of months, but
> the maximum and minimum are not that meaningful over such a long
> period. You might well want to keep a longer-term average while
> seeing the maximum and minimum for, say, today. I don't know exactly
> how useful that is, but it doesn't seem obviously dumb.

Well, maybe it's okay, but not being able to reset the stddev state seems
odd, and the chosen function name seems odder. In any case, the time to
be discussing the design of such functionality was several months ago.
I'm still for ripping it out for 9.4, rather than being stuck with
behavior that's not been adequately discussed.

regards, tom lane