Re: [PoC] Reducing planning time when tables have many partitions

Hi David,

Impressive results!

On Fri, Apr 4, 2025 at 3:05 PM David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> I've done some further work on this, mostly relating to the code
> comments.

It looks to me like the following hunks in 0002 probably belong in
0001, unless you’re planning to commit the patches together anyway:

diff --git a/src/backend/optimizer/path/indxpath.c
b/src/backend/optimizer/path/indxpath.c
index 6386ce82253..5c6410e0631 100644
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -190,7 +190,7 @@ static IndexClause
*expand_indexqual_rowcompare(PlannerInfo *root,
IndexOptInfo *index,
Oid expr_op,
bool var_on_left);
-static void match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
+static void match_pathkeys_to_index(PlannerInfo *root, IndexOptInfo
*index, List *pathkeys,
List **orderby_clauses_p,
List **clause_columns_p);
static Expr *match_clause_to_ordering_op(IndexOptInfo *index,
@@ -934,7 +934,7 @@ build_index_paths(PlannerInfo *root, RelOptInfo *rel,
* query_pathkeys will allow an incremental sort to be considered on
* the index's partially sorted results.
*/
- match_pathkeys_to_index(index, root->query_pathkeys,
+ match_pathkeys_to_index(root, index, root->query_pathkeys,
&orderbyclauses,
&orderbyclausecols);
if (list_length(root->query_pathkeys) == list_length(orderbyclauses))

The comment on EquivalenceMember might benefit from a mention of how
ec_childmembers now fits into the picture -- do you think it’s worth
updating?

/*
* EquivalenceMember - one member expression of an EquivalenceClass
*
* em_is_child signifies that this element was built by transposing a member
* for an appendrel parent relation to represent the corresponding expression
* for an appendrel child.
...

+ /* XXX ec_childmembers? */

Maybe we don’t need to print these, since the comment on em_is_child
suggests they aren’t really full-fledged EC members and are meant to
be ignored by most operations?

--
Thanks, Amit Langote