On Sun, Jun 13, 2021 at 1:29 PM Tomas Vondra <tomas.von...@enterprisedb.com> wrote:
> Hi, > > Here is a slightly updated version of the patch - rebased to current > master and fixing some minor issues to handle expressions (and not just > the Var nodes as before). > > The changes needed to support (Expr op Expr) are mostly mechanical, > though I'm sure the code needs some cleanup. The main issue I ran into > is the special case clauselist_selectivity, which does > > if (list_length(clauses) == 1) > return clause_selectivity_ext(...); > > which applies to cases like "WHERE a < b" which can now be handled by > extended statistics, thanks to this patch. But clause_selectivity_ext > only used to call restriction_selectivity for these clauses, which does > not use extended statistics, of course. > > I considered either getting rid of the special case, passing everything > through extended stats, including cases with a single clause. But that > ends up affecting e.g. OR clauses, so I tweaked clause_selectivity_ext a > bit, which seems like a better approach. > > > regards > > -- > Tomas Vondra > EnterpriseDB: http://www.enterprisedb.com > The Enterprise PostgreSQL Company > Hi, - for (i = 0; i < mcvlist->nitems; i++) + if (cst) /* Expr op Const */ It seems the Const op Expr is also covered by this if branch. Hence the comment should include this case. Cheers
