RE: speeding up planning with partitions

About inheritance_make_rel_from_joinlist(), I considered how it processes
joins for sub-partitioned-table.

sub-partitioned-table image:
part
  sub1
    leaf1
    leaf2

inheritance_make_rel_from_joinlist() translates join_list and join_info_list
for each leafs(leaf1, leaf2 in above image). To translate those two lists for
leaf1, inheritance_make_rel_from_joinlist() translates lists from part to sub1
and nextly from sub1 to leaf1. For leaf2, inheritance_make_rel_from_joinlist() 
translates lists from part to sub1 and from sub1 to leaf2. There are same
translation from part to sub1, and I think it is better if we can eliminate it.
I attached 0002-delta.patch.

In the patch, inheritance_make_rel_from_joinlist() translates lists not only for
leafs but for mid-nodes, in a depth-first manner, so it can use lists of
mid-nodes for translating lists from mid-node to leafs, which eliminates same
translation.

I think it might be better if we can apply same logic to inheritance_planner(),
which once implemented the same logic as below. 


    foreach(lc, root->append_rel_list)
    {
        AppendRelInfo *appinfo = lfirst_node(AppendRelInfo, lc);
        ...
        /*
         * expand_inherited_rtentry() always processes a parent before any of
         * that parent's children, so the parent_root for this relation should
         * already be available.
         */
        parent_root = parent_roots[appinfo->parent_relid];
        Assert(parent_root != NULL);
        parent_parse = parent_root->parse;
        ...
        subroot->parse = (Query *)
            adjust_appendrel_attrs(parent_root,
                                   (Node *) parent_parse,
                                   1, &appinfo);


--
Yoshikazu Imai