On 06/07/2019 15:58, Tom Lane wrote: > Ancoron Luciferis <ancoron.luciferis@xxxxxxxxxxxxxx> writes: >> I've been wondering whether it is possible somehow to have the standard >> column statistics to respect a certain operator class? > > In principle, pg_statistic can represent stats for a non-default opclass. > Teaching ANALYZE to collect such stats when appropriate, and then teaching > the planner to use them when appropriate, is left as an exercise for the > reader. Hehe, now that you are saying it, I realize what I was actually asking for with this... ;) > > I think the "when appropriate" bit is actually the hardest part of that. > Possibly, if you were satisfied with a relatively manual approach, > you could proceed by using CREATE STATISTICS to declare interest in > keeping standard stats for a non-default sort order. Not sure what to > do if you want it to be automatic, because I don't think people would > hold still for having ANALYZE collect stats for any random non-default > opclass automatically. Maybe a new opclass property? I totally agree with the complications around all that. Now I think if I want better statistics and better plans for my new time-sorted index, I will need a new data type for which I can set the opclass as default, which also would provide users the guarantee that they'll get what they expect. Thanx and cheers, Ancoron
