1 files changed, 23 insertions, 22 deletions

diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 982d16c6c88..4fbb5c1e746 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -1516,22 +1516,20 @@ CheckVarSlotCompatibility(TupleTableSlot *slot, int attnum, Oid vartype)
 {
 	/*
 	 * What we have to check for here is the possibility of an attribute
-	 * having been changed in type since the plan tree was created.  Ideally
-	 * the plan will get invalidated and not re-used, but just in case, we
-	 * keep these defenses.  Fortunately it's sufficient to check once on the
-	 * first time through.
-	 *
-	 * System attributes don't require checking since their types never
-	 * change.
-	 *
-	 * Note: we allow a reference to a dropped attribute.  slot_getattr will
-	 * force a NULL result in such cases.
+	 * having been dropped or changed in type since the plan tree was created.
+	 * Ideally the plan will get invalidated and not re-used, but just in
+	 * case, we keep these defenses.  Fortunately it's sufficient to check
+	 * once on the first time through.
 	 *
 	 * Note: ideally we'd check typmod as well as typid, but that seems
 	 * impractical at the moment: in many cases the tupdesc will have been
 	 * generated by ExecTypeFromTL(), and that can't guarantee to generate an
 	 * accurate typmod in all cases, because some expression node types don't
-	 * carry typmod.
+	 * carry typmod.  Fortunately, for precisely that reason, there should be
+	 * no places with a critical dependency on the typmod of a value.
+	 *
+	 * System attributes don't require checking since their types never
+	 * change.
 	 */
 	if (attnum > 0)
 	{
@@ -1544,17 +1542,20 @@ CheckVarSlotCompatibility(TupleTableSlot *slot, int attnum, Oid vartype)
 
 		attr = slot_tupdesc->attrs[attnum - 1];
 
-		/* can't check type if dropped, since atttypid is probably 0 */
-		if (!attr->attisdropped)
-		{
-			if (vartype != attr->atttypid)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATATYPE_MISMATCH),
-						 errmsg("attribute %d has wrong type", attnum),
-						 errdetail("Table has type %s, but query expects %s.",
-								   format_type_be(attr->atttypid),
-								   format_type_be(vartype))));
-		}
+		if (attr->attisdropped)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+					 errmsg("attribute %d of type %s has been dropped",
+							attnum, format_type_be(slot_tupdesc->tdtypeid))));
+
+		if (vartype != attr->atttypid)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("attribute %d of type %s has wrong type",
+							attnum, format_type_be(slot_tupdesc->tdtypeid)),
+					 errdetail("Table has type %s, but query expects %s.",
+							   format_type_be(attr->atttypid),
+							   format_type_be(vartype))));
 	}
 }