Re: Add min and max execute statement time in pg_stat_statement

On 02/17/2015 08:21 PM, Peter Eisentraut wrote:
> On 1/20/15 6:32 PM, David G Johnston wrote:
>> In fact, as far as
>> the database knows, the values provided to this function do represent an
>> entire population and such a correction would be unnecessary.  I guess it
>> boils down to whether "future" queries are considered part of the population
>> or whether the population changes upon each query being run and thus we are
>> calculating the ever-changing population variance.
> I think we should be calculating the population variance.  We are
> clearly taking the population to be all past queries (from the last
> reset point).  Otherwise calculating min and max wouldn't make sense.
>
>

The difference is likely to be very small in any case where you actually 
want to examine the standard deviation, so I feel we're rather arguing 
about how many angels can fit on the head of a pin, but if this is the 
consensus I'll change it.

cheers

andrew