From aefe619b1cecb4ca70f2035b2b62ff270a4e80e7 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@2ndquadrant.com>
Date: Tue, 3 Nov 2020 03:22:50 +0100
Subject: [PATCH 2/3] partially revert ba3e76cc571eba3dea19c9465ff15ac3ac186576

---
 contrib/postgres_fdw/postgres_fdw.c     | 29 +++++++++++++++++++++++++
 src/backend/optimizer/path/equivclass.c | 29 -------------------------
 src/include/optimizer/paths.h           |  1 -
 3 files changed, 29 insertions(+), 30 deletions(-)

diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 9c5aaacc51..dcf533d700 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -6524,6 +6524,35 @@ conversion_error_callback(void *arg)
 	}
 }
 
+/*
+ * Find an equivalence class member expression, all of whose Vars, come from
+ * the indicated relation.
+ */
+Expr *
+find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel)
+{
+	ListCell   *lc_em;
+
+	foreach(lc_em, ec->ec_members)
+	{
+		EquivalenceMember *em = lfirst(lc_em);
+
+		if (bms_is_subset(em->em_relids, rel->relids) &&
+			!bms_is_empty(em->em_relids))
+		{
+			/*
+			 * If there is more than one equivalence member whose Vars are
+			 * taken entirely from this relation, we'll be content to choose
+			 * any one of those.
+			 */
+			return em->em_expr;
+		}
+	}
+
+	/* We didn't find any suitable equivalence class expression */
+	return NULL;
+}
+
 /*
  * Find an equivalence class member expression to be computed as a sort column
  * in the given target.
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index f98fd7b3eb..a507a76bcf 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -768,35 +768,6 @@ get_eclass_for_sort_expr(PlannerInfo *root,
 	return newec;
 }
 
-/*
- * Find an equivalence class member expression, all of whose Vars, come from
- * the indicated relation.
- */
-Expr *
-find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel)
-{
-	ListCell   *lc_em;
-
-	foreach(lc_em, ec->ec_members)
-	{
-		EquivalenceMember *em = lfirst(lc_em);
-
-		if (bms_is_subset(em->em_relids, rel->relids) &&
-			!bms_is_empty(em->em_relids))
-		{
-			/*
-			 * If there is more than one equivalence member whose Vars are
-			 * taken entirely from this relation, we'll be content to choose
-			 * any one of those.
-			 */
-			return em->em_expr;
-		}
-	}
-
-	/* We didn't find any suitable equivalence class expression */
-	return NULL;
-}
-
 /*
  * Find an equivalence class member expression that can be safely used by a
  * sort node on top of the provided relation. The rules here must match those
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 8a4c6f8b59..5f6ffbd860 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -134,7 +134,6 @@ extern EquivalenceClass *get_eclass_for_sort_expr(PlannerInfo *root,
 												  Index sortref,
 												  Relids rel,
 												  bool create_it);
-extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
 extern Expr *find_em_expr_usable_for_sorting_rel(EquivalenceClass *ec, RelOptInfo *rel);
 extern void generate_base_implied_equalities(PlannerInfo *root);
 extern List *generate_join_implied_equalities(PlannerInfo *root,
-- 
2.25.4