Re: Statistics and selectivity estimation for ranges

On Wed, Aug 15, 2012 at 12:14 PM, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote:

Histogram of upper bounds would be both more
accurate and natural for some operators. However, it requires collecting
additional statistics while AFAICS it doesn't liberate us from having
histogram of range lengths.

Hmm, if we collected a histogram of lower bounds and a histogram of upper bounds, that would be roughly the same amount of data as for the "standard" histogram with both bounds in the same histogram.

Ok, we've to decide if we need "standard" histogram. In some cases it can be used for more accurate estimation of < and > operators. ------
With best regards,
Alexander Korotkov.