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
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