On Fri, Mar 18, 2016 at 3:29 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > 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.
Oh, cool. > 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. I haven't studied the patch series in enough detail to have an educated opinion on that. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers