From 231479b128c08b845fbc78e682e6c54e9e7e2141 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Tue, 19 Jun 2018 13:34:31 +0300
Subject: [PATCH 3/4] Move find_em_expr_for_rel() into the backend.

---
 contrib/postgres_fdw/deparse.c          |  1 +
 contrib/postgres_fdw/postgres_fdw.c     | 28 ----------------------------
 contrib/postgres_fdw/postgres_fdw.h     |  1 -
 src/backend/optimizer/path/equivclass.c | 29 +++++++++++++++++++++++++++++
 src/include/optimizer/paths.h           |  1 +
 5 files changed, 31 insertions(+), 29 deletions(-)

diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index d272719ff4..6b3178350f 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -49,6 +49,7 @@
 #include "nodes/nodeFuncs.h"
 #include "nodes/plannodes.h"
 #include "optimizer/clauses.h"
+#include "optimizer/paths.h"
 #include "optimizer/prep.h"
 #include "optimizer/tlist.h"
 #include "optimizer/var.h"
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 78b0f43ca8..7906ade920 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -5767,31 +5767,3 @@ conversion_error_callback(void *arg)
 			errcontext("column \"%s\" of foreign table \"%s\"", attname, relname);
 	}
 }
-
-/*
- * 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))
-		{
-			/*
-			 * 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;
-}
diff --git a/contrib/postgres_fdw/postgres_fdw.h b/contrib/postgres_fdw/postgres_fdw.h
index a5d4011e8d..16965fc820 100644
--- a/contrib/postgres_fdw/postgres_fdw.h
+++ b/contrib/postgres_fdw/postgres_fdw.h
@@ -172,7 +172,6 @@ extern void deparseAnalyzeSizeSql(StringInfo buf, Relation rel);
 extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
 				  List **retrieved_attrs);
 extern void deparseStringLiteral(StringInfo buf, const char *val);
-extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
 extern List *build_tlist_to_deparse(RelOptInfo *foreignrel);
 extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root,
 						RelOptInfo *foreignrel, List *tlist,
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index b22b36ec0e..b8a0a2e29b 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -2511,3 +2511,32 @@ is_redundant_derived_clause(RestrictInfo *rinfo, List *clauselist)
 
 	return false;
 }
+
+/*
+ * find_em_expr_for_rel
+ *		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))
+		{
+			/*
+			 * 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;
+}
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 89835ad259..39e3e8f85c 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -188,6 +188,7 @@ extern bool eclass_useful_for_merging(PlannerInfo *root,
 						  EquivalenceClass *eclass,
 						  RelOptInfo *rel);
 extern bool is_redundant_derived_clause(RestrictInfo *rinfo, List *clauselist);
+extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
 
 /*
  * pathkeys.c
-- 
2.11.0