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