diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index e59f38b6ce0..329419c38d9 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -38,8 +38,6 @@ static EquivalenceMember *add_eq_member(EquivalenceClass *ec,
 										JoinDomain *jdomain,
 										EquivalenceMember *parent,
 										Oid datatype);
-static void add_eq_source(PlannerInfo *root, EquivalenceClass *ec,
-						  RestrictInfo *rinfo);
 static void add_eq_derive(PlannerInfo *root, EquivalenceClass *ec,
 						  RestrictInfo *rinfo);
 static bool is_exprlist_member(Expr *node, List *exprs);
@@ -78,6 +76,49 @@ static Bitmapset *get_eclass_indexes_for_relids(PlannerInfo *root,
 static Bitmapset *get_common_eclass_indexes(PlannerInfo *root, Relids relids1,
 											Relids relids2);
 
+/*
+ * add_eq_source - add 'rinfo' in eq_sources for this 'ec'
+ */
+void
+add_eq_source(PlannerInfo *root, EquivalenceClass *ec, RestrictInfo *rinfo)
+{
+	int			source_idx = list_length(root->eq_sources);
+	int			i;
+
+	ec->ec_source_indexes = bms_add_member(ec->ec_source_indexes, source_idx);
+	root->eq_sources = lappend(root->eq_sources, rinfo);
+
+	i = -1;
+	while ((i = bms_next_member(rinfo->clause_relids, i)) >= 0)
+	{
+		RangeTblEntry *rte = root->simple_rte_array[i];
+
+		rte->eclass_source_indexes = bms_add_member(rte->eclass_source_indexes,
+													source_idx);
+	}
+}
+
+/*
+ * add_eq_derive - add 'rinfo' in eq_derives for this 'ec'
+ */
+static void
+add_eq_derive(PlannerInfo *root, EquivalenceClass *ec, RestrictInfo *rinfo)
+{
+	int			derive_idx = list_length(root->eq_derives);
+	int			i;
+
+	ec->ec_derive_indexes = bms_add_member(ec->ec_derive_indexes, derive_idx);
+	root->eq_derives = lappend(root->eq_derives, rinfo);
+
+	i = -1;
+	while ((i = bms_next_member(rinfo->clause_relids, i)) >= 0)
+	{
+		RangeTblEntry *rte = root->simple_rte_array[i];
+
+		rte->eclass_derive_indexes = bms_add_member(rte->eclass_derive_indexes,
+													derive_idx);
+	}
+}
 
 /*
  * process_equivalence
@@ -561,51 +602,6 @@ add_eq_member(EquivalenceClass *ec, Expr *expr, Relids relids,
 	return em;
 }
 
-/*
- * add_eq_source - add 'rinfo' in eq_sources for this 'ec'
- */
-static void
-add_eq_source(PlannerInfo *root, EquivalenceClass *ec, RestrictInfo *rinfo)
-{
-	int			source_idx = list_length(root->eq_sources);
-	int			i;
-
-	ec->ec_source_indexes = bms_add_member(ec->ec_source_indexes, source_idx);
-	root->eq_sources = lappend(root->eq_sources, rinfo);
-
-	i = -1;
-	while ((i = bms_next_member(rinfo->clause_relids, i)) >= 0)
-	{
-		RangeTblEntry *rte = root->simple_rte_array[i];
-
-		rte->eclass_source_indexes = bms_add_member(rte->eclass_source_indexes,
-													source_idx);
-	}
-}
-
-/*
- * add_eq_derive - add 'rinfo' in eq_derives for this 'ec'
- */
-static void
-add_eq_derive(PlannerInfo *root, EquivalenceClass *ec, RestrictInfo *rinfo)
-{
-	int			derive_idx = list_length(root->eq_derives);
-	int			i;
-
-	ec->ec_derive_indexes = bms_add_member(ec->ec_derive_indexes, derive_idx);
-	root->eq_derives = lappend(root->eq_derives, rinfo);
-
-	i = -1;
-	while ((i = bms_next_member(rinfo->clause_relids, i)) >= 0)
-	{
-		RangeTblEntry *rte = root->simple_rte_array[i];
-
-		rte->eclass_derive_indexes = bms_add_member(rte->eclass_derive_indexes,
-													derive_idx);
-	}
-}
-
-
 /*
  * get_eclass_for_sort_expr
  *	  Given an expression and opfamily/collation info, find an existing
@@ -3398,18 +3394,6 @@ get_ec_source_indexes(PlannerInfo *root, EquivalenceClass *ec, Relids relids)
 		rel_esis = bms_add_members(rel_esis, rte->eclass_source_indexes);
 	}
 
-#ifdef USE_ASSERT_CHECKING
-	/* verify the results look sane */
-	i = -1;
-	while ((i = bms_next_member(rel_esis, i)) >= 0)
-	{
-		RestrictInfo *rinfo = list_nth_node(RestrictInfo, root->eq_sources,
-											i);
-
-		Assert(bms_overlap(relids, rinfo->clause_relids));
-	}
-#endif
-
 	/* bitwise-AND to leave only the ones for this EquivalenceClass */
 	return bms_int_members(rel_esis, ec->ec_source_indexes);
 }
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 0298c26166f..92dcbbdf2e0 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -61,7 +61,7 @@ static void remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
 										  SpecialJoinInfo *sjinfo);
 static void remove_rel_from_restrictinfo(RestrictInfo *rinfo,
 										 int relid, int ojrelid);
-static void remove_rel_from_eclass(EquivalenceClass *ec,
+static void remove_rel_from_eclass(PlannerInfo *root, EquivalenceClass *ec,
 								   int relid, int ojrelid);
 static List *remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved);
 static bool rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel);
@@ -578,7 +578,7 @@ remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
 
 		if (bms_is_member(relid, ec->ec_relids) ||
 			bms_is_member(ojrelid, ec->ec_relids))
-			remove_rel_from_eclass(ec, relid, ojrelid);
+			remove_rel_from_eclass(root, ec, relid, ojrelid);
 	}
 
 	/*
@@ -663,7 +663,7 @@ remove_rel_from_restrictinfo(RestrictInfo *rinfo, int relid, int ojrelid)
  * level(s).
  */
 static void
-remove_rel_from_eclass(EquivalenceClass *ec, int relid, int ojrelid)
+remove_rel_from_eclass(PlannerInfo *root, EquivalenceClass *ec, int relid, int ojrelid)
 {
 	ListCell   *lc;
 	int			i;
@@ -1530,6 +1530,24 @@ replace_relid(Relids relids, int oldId, int newId)
 	return relids;
 }
 
+void
+del_eq_derives(PlannerInfo *root, EquivalenceClass *ec)
+{
+	int i = -1;
+
+	while ((i = bms_next_member(ec->ec_derive_indexes, i)) >= 0)
+	{
+		/*
+		 * Can't delete the element because we would need to rebuild all
+		 * the eq_derives indexes. But add a nuke to detect potential problems.
+		 */
+		list_nth_cell(root->eq_derives, i)->ptr_value = NULL;
+	}
+	bms_free(ec->ec_derive_indexes);
+	ec->ec_derive_indexes = NULL;
+}
+
+
 /*
  * Update EC members to point to the remaining relation instead of the removed
  * one, removing duplicates.
@@ -1553,10 +1571,11 @@ replace_relid(Relids relids, int oldId, int newId)
  * delete them.
  */
 static void
-update_eclasses(EquivalenceClass *ec, int from, int to)
+update_eclass(PlannerInfo *root, EquivalenceClass *ec, int from, int to)
 {
 	List	   *new_members = NIL;
 	List	   *new_sources = NIL;
+	int			i = -1;
 	ListCell   *lc;
 	ListCell   *lc1;
 
@@ -1595,16 +1614,13 @@ update_eclasses(EquivalenceClass *ec, int from, int to)
 			new_members = lappend(new_members, em);
 	}
 
-	list_free(ec->ec_members);
-	ec->ec_members = new_members;
-
-	list_free(ec->ec_derives);
-	ec->ec_derives = NULL;
+	del_eq_derives(root, ec);
 
 	/* Update EC source expressions */
-	foreach(lc, ec->ec_sources)
+	while ((i = bms_next_member(ec->ec_source_indexes, i)) > 0)
 	{
-		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
+		RestrictInfo   *rinfo = list_nth_node(RestrictInfo,
+											   root->eq_sources, i);
 		bool		is_redundant = false;
 
 		if (!bms_is_member(from, rinfo->required_relids))
@@ -1638,8 +1654,21 @@ update_eclasses(EquivalenceClass *ec, int from, int to)
 			new_sources = lappend(new_sources, rinfo);
 	}
 
-	list_free(ec->ec_sources);
-	ec->ec_sources = new_sources;
+	i=-1;
+
+	while ((i = bms_next_member(ec->ec_source_indexes, i)) > 0)
+	{
+		list_nth_cell(root->eq_sources, i)->ptr_value = NULL;
+	}
+	bms_free(ec->ec_source_indexes);
+	ec->ec_source_indexes = NULL;
+
+	foreach(lc, new_sources)
+	{
+		RestrictInfo   *rinfo = lfirst_node(RestrictInfo, lc);
+		add_eq_source(root, ec, rinfo);
+	}
+
 	ec->ec_relids = replace_relid(ec->ec_relids, from, to);
 }
 
@@ -1817,7 +1846,7 @@ remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
 	{
 		EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
 
-		update_eclasses(ec, toRemove->relid, toKeep->relid);
+		update_eclass(root, ec, toRemove->relid, toKeep->relid);
 		toKeep->eclass_indexes = bms_add_member(toKeep->eclass_indexes, i);
 	}
 
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 469ca518571..83695e2f66f 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -111,6 +111,9 @@ extern bool have_join_order_restriction(PlannerInfo *root,
 extern bool have_dangerous_phv(PlannerInfo *root,
 							   Relids outer_relids, Relids inner_params);
 extern void mark_dummy_rel(RelOptInfo *rel);
+extern void del_eq_derives(PlannerInfo *root, EquivalenceClass *ec);
+extern void add_eq_source(PlannerInfo *root, EquivalenceClass *ec, RestrictInfo *rinfo);
+
 
 /*
  * equivclass.c