On 12 July 2014 23:25, Emre Hasegeli Wrote, > > I have one last comment, after clarifying this I can move it to > "ready for committer". > > 1. In networkjoinsel, For avoiding the case of huge statistics, only > some of the values from mcv and histograms are used (calculated using > SQRT). > > -- But in my opinion, if histograms and mcv both are exist then its > fine, but if only mcv's are there in that case, we can match complete > MCV, it will give better accuracy. > > In other function like eqjoinsel also its matching complete MCV. > > I was not sure of reducing statistics, at all. I could not find any > other selectivity estimation function which does this. After testing > it some more, I reached the conclusion that it would be better to only > reduce the values of the outer loop on histogram match. Now it matches > complete MCV lists to each other. I also switched back to > log2() from sqrt() to make the outer list smaller.
OK > > I rethink your previous advice to threat histogram bucket partially > matched when the constant matches the last boundary, and changed it > that way. It is better than using the selectivity for only one value. > Removing this part also make the function more simple. The new version > of the patch attached. This seems good to me. > > While looking at it I find some other small problems and fixed them. > I also realized that I forgot to support other join types than inner > join. Currently, the default estimation is used for anti joins. > I think the patch will need more than trivial amount of change to > support anti joins. I can work on it later. While doing it, outer > join selectivity estimation can also be improved. I think the patch is > better than nothing in its current state. I agree with you that we can support other join type and anti join later, If others don’t have any objection in doing other parts later I will mark as "Ready For Committer". Regards, Dilip -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers