On Wed, Aug 3, 2016 at 4:58 AM, Tomas Vondra <tomas.von...@2ndquadrant.com> wrote: > 2) combining multiple statistics > > I think the ability to combine multivariate statistics (covering different > subsets of conditions) is important and useful, but I'm starting to think > that the current implementation may not be the correct one (which is why I > haven't written the SGML docs about this part of the patch series yet).
While researching this topic a few years ago I came across a paper on this exact topic called "Consistently Estimating the Selectivity of Conjuncts of Predicates" [1]. While effective it seems to be quite heavy-weight, so would probably need support for tiered optimization. [1] https://courses.cs.washington.edu/courses/cse544/11wi/papers/markl-vldb-2005.pdf Regards, Ants Aasma -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
