0002-Special-purpose-generate_join_implied_equalities-imp.patch

From 5757eaaec4fda492957cb829e9c261e2e7e1ede0 Mon Sep 17 00:00:00 2001
From: "dgrowley@gmail.com" <dgrowley@gmail.com>
Date: Thu, 18 Jul 2019 18:31:25 +1200
Subject: [PATCH 2/2] Special purpose generate_join_implied_equalities
 implementation

---
 src/backend/optimizer/path/equivclass.c | 68 +++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index 6e7db4b969..c82d5d97ef 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -1127,11 +1127,69 @@ generate_join_implied_equalities(PlannerInfo *root,
 								 Relids outer_relids,
 								 RelOptInfo *inner_rel)
 {
-	return generate_join_implied_equalities_for_ecs(root,
-													root->eq_classes,
-													join_relids,
-													outer_relids,
-													inner_rel);
+	List	   *result = NIL;
+	Relids		inner_relids = inner_rel->relids;
+	Relids		nominal_inner_relids;
+	Relids		nominal_join_relids;
+	Bitmapset * matching_ecs;
+	int			i;
+
+	/* If inner rel is a child, extra setup work is needed */
+	if (IS_OTHER_REL(inner_rel))
+	{
+		Assert(!bms_is_empty(inner_rel->top_parent_relids));
+
+		/* Fetch relid set for the topmost parent rel */
+		nominal_inner_relids = inner_rel->top_parent_relids;
+		/* ECs will be marked with the parent's relid, not the child's */
+		nominal_join_relids = bms_union(outer_relids, nominal_inner_relids);
+	}
+	else
+	{
+		nominal_inner_relids = inner_relids;
+		nominal_join_relids = join_relids;
+	}
+
+	/* Get all eclasses in common between inner_relids and join_relids */
+	matching_ecs = get_common_eclass_indexes(root, inner_relids, join_relids);
+
+	i = -1;
+	while ((i = bms_next_member(matching_ecs, i)) >= 0)
+	{
+		EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
+		List	   *sublist = NIL;
+
+		/* ECs containing consts do not need any further enforcement */
+		if (ec->ec_has_const)
+			continue;
+
+		/* Single-member ECs won't generate any deductions */
+		if (list_length(ec->ec_members) <= 1)
+			continue;
+
+		/* Sanity check that this eclass overlaps the join */
+		Assert(bms_overlap(ec->ec_relids, nominal_join_relids));
+
+		if (!ec->ec_broken)
+			sublist = generate_join_implied_equalities_normal(root,
+															  ec,
+															  join_relids,
+															  outer_relids,
+															  inner_relids);
+
+		/* Recover if we failed to generate required derived clauses */
+		if (ec->ec_broken)
+			sublist = generate_join_implied_equalities_broken(root,
+															  ec,
+															  nominal_join_relids,
+															  outer_relids,
+															  nominal_inner_relids,
+															  inner_rel);
+
+		result = list_concat(result, sublist);
+	}
+
+	return result;
 }
 
 /*
-- 
2.17.1