Re: Statistics and selectivity estimation for ranges

On 01.03.2013 16:22, Alexander Korotkov wrote:

On Tue, Mar 12, 2013 at 8:03 PM, Heikki Linnakangas<hlinnakangas@vmware.com

wrote:

So, after some hacking, I ended up with this version. I find it more
readable, I hope I didn't miss anything. This seems to produce results that
are close, but not identical, to the original patch. I'm not sure where the
discrepancy is coming from, or which patch is more correct in that respect.
I'll continue from this tomorrow, but if you have the time, please take a
look and let me know what you think.

I've read your explanation and version of patch. In general it seems
correct to me.
There is one point why I have breaked up abstraction in some functions is
infinities. For example, in calc_length_hist_frac one or both of length1
and length2 can be infinity. In the line

frac = area / (length2 - length1);

you can get NaN result. I've especially adjusted the code to get more of
less correct result in this case.

Hmm, good point. I think I managed to fix those cases in the attached version. Is there any other corner case that I missed?