Robert Haas <robertmh...@gmail.com> writes: > On Wed, Apr 29, 2015 at 12:33 PM, Tomas Vondra > <tomas.von...@2ndquadrant.com> wrote: >> On 04/29/15 18:26, Tom Lane wrote: >>> But there are basic reasons why expression_tree_walker should not try >>> to deal with RestrictInfos; the most obvious one being that it's not >>> clear whether it should descend into both the basic and OR-clause >>> subtrees. Also, if a node has expression_tree_walker support then it >>> should logically have expression_tree_mutator support as well, but >>> that's got multiple issues. RestrictInfos are not supposed to be >>> copied once created; and the mutator couldn't detect whether their >>> derived fields are still valid.
>> OK, I do understand that. So what about pull_varnos_walker and >> pull_varattnos_walker - what about teaching them about RestrictInfos? > This patch has become part 1 of many under the "multivariate > statistics vNNN" family of threads, but I guess it would be helpful if > you could opine on the reasonable-ness of this approach. I don't want > to commit anything over your objections, but this kind of tailed off > without a conclusion. I'm up to my ears in psql at the moment, but hope to get to the multivariate stats patch later, maybe next week. In the meantime, I remain of the opinion that RestrictInfo is not an expression node and wanting expression_tree_walker to handle it is wrong. I'm suspicious about pull_varnos; it might be all right given that we can assume the same Vars are in both subtrees, but I still don't really see why that one function has suddenly grown this need when others have not. regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers