3 files changed, 13 insertions, 5 deletions
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index cad9f28ef5d..fe67baf1420 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -80,11 +80,13 @@ makeVar(int varno,
 	var->varlevelsup = varlevelsup;
 
 	/*
-	 * Only a few callers need to make Var nodes with varnosyn/varattnosyn
-	 * different from varno/varattno.  We don't provide separate arguments for
-	 * them, but just initialize them to the given varno/varattno.  This
-	 * reduces code clutter and chance of error for most callers.
+	 * Only a few callers need to make Var nodes with non-null varnullingrels,
+	 * or with varnosyn/varattnosyn different from varno/varattno.  We don't
+	 * provide separate arguments for them, but just initialize them to NULL
+	 * and the given varno/varattno.  This reduces code clutter and chance of
+	 * error for most callers.
 	 */
+	var->varnullingrels = NULL;
 	var->varnosyn = (Index) varno;
 	var->varattnosyn = varattno;
 
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 8fc24c882b6..dc8415a693c 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -2641,6 +2641,7 @@ expression_tree_mutator_impl(Node *node,
 				Var		   *newnode;
 
 				FLATCOPY(newnode, var, Var);
+				/* Assume we need not copy the varnullingrels bitmapset */
 				return (Node *) newnode;
 			}
 			break;
@@ -3234,7 +3235,7 @@ expression_tree_mutator_impl(Node *node,
 
 				FLATCOPY(newnode, phv, PlaceHolderVar);
 				MUTATE(newnode->phexpr, phv->phexpr, Expr *);
-				/* Assume we need not copy the relids bitmapset */
+				/* Assume we need not copy the relids bitmapsets */
 				return (Node *) newnode;
 			}
 			break;
diff --git a/src/backend/nodes/queryjumblefuncs.c b/src/backend/nodes/queryjumblefuncs.c
index 16084842a36..8b101fc336c 100644
--- a/src/backend/nodes/queryjumblefuncs.c
+++ b/src/backend/nodes/queryjumblefuncs.c
@@ -383,6 +383,11 @@ JumbleExpr(JumbleState *jstate, Node *node)
 				APP_JUMB(var->varno);
 				APP_JUMB(var->varattno);
 				APP_JUMB(var->varlevelsup);
+
+				/*
+				 * We can omit varnullingrels, because it's fully determined
+				 * by varno/varlevelsup plus the Var's query location.
+				 */
 			}
 			break;
 		case T_Const: