Andy Fan <zhihui.fan1...@gmail.com> wrote: > > 1) v14-0001-Introduce-RelInfoList-structure.patch > > ------------------------------------------------- > > > > - I'm not entirely sure why we need this change. We had the list+hash > > before, so I assume we do this because we need the output functions? > > I believe that this is what Tom proposed in [1], see "Maybe an appropriate > preliminary patch is to refactor the support code ..." near the end of that > message. The point is that now we need two lists: one for "plain" relations > and one for grouped ones. > > > I guess what Toms suggested[1] is to store the the grouped ones into > root->upper_rels rather than a separated member, see fetch_upper_rel > or UpperRelationKind. If we do need the list+hash method for long list > lookup, > we can merge it into upper_rels. If we want this benefits at other place > rather > than root->upper_rels, we can store a generic type in RelInfoList, looks > currently > it is bounded to RelAggInfo besides RelOptInfo. But overall, personally I > think we can > ignore such optimization at the first stage to save the attention of the core > reviewers > since they are too precious :) Just FYI > > [1] https://www.postgresql.org/message-id/9726.1542577...@sss.pgh.pa.us
Hm, you seem to be right, not sure why I missed the point. I thought that the reason Tom doesn't like storing the grouped relations in simple_rel_array is that we only need the grouped base relations inside query_planner(), but simple_rel_array is used higher in the stack. So I introduced a new field and used it only in query_planner() and subroutines. Yes, it's better to use root->upper_rels than to introduce the new field. I'll adjust the patch. Thanks. -- Antonin Houska Web: https://www.cybertec-postgresql.com
