Hello Hackers, To improve selectivities of queries I suggest to add support of multidimensional histograms as described in paper [1].
To query multidimensional histograms efficiently we can use H-trees as described in paper [2]. Postgres has limited support of multivariate statistics: * MCV only useful for columns with small number of distinct values; * functional dependencies only reflect dependencies among columns (not column values). [1] http://www.cs.cmu.edu/~rcarlson/docs/RyanCarlson_databases.pdf [2] https://dl.acm.org/doi/pdf/10.1145/50202.50205 -- Regards, Alexander Cheshev
