Small cleanups in fast default code.

Problems identified by Andres Freund and Haribabu Kommi

src/backend/access/common/heaptuple.c

@@ -127,7 +127,6 @@ slot_getmissingattrs(TupleTableSlot *slot, int startAttNum, int lastAttNum)
 	if (slot->tts_tupleDescriptor->constr)
 		attrmiss = slot->tts_tupleDescriptor->constr->missing;
 
-
 	if (!attrmiss)
 	{
 		/* no missing values array at all, so just fill everything in as NULL */
@@ -139,9 +138,9 @@ slot_getmissingattrs(TupleTableSlot *slot, int startAttNum, int lastAttNum)
 	else
 	{
 		/* if there is a missing values array we must process them one by one */
-		for (missattnum = lastAttNum - 1;
-			 missattnum >= startAttNum;
-			 missattnum--)
+		for (missattnum = startAttNum;
+			 missattnum < lastAttNum;
+			 missattnum++)
 		{
 			slot->tts_values[missattnum] = attrmiss[missattnum].ammissing;
 			slot->tts_isnull[missattnum] =
@@ -1636,6 +1635,8 @@ slot_getallattrs(TupleTableSlot *slot)
 
 	slot_deform_tuple(slot, attnum);
 
+	attnum = slot->tts_nvalid;
+
 	/*
 	 * If tuple doesn't have all the atts indicated by tupleDesc, read the
 	 * rest as NULLS or missing values.
@@ -1681,8 +1682,10 @@ slot_getsomeattrs(TupleTableSlot *slot, int attnum)
 
 	slot_deform_tuple(slot, attno);
 
+	attno = slot->tts_nvalid;
+
 	/*
-	 * If tuple doesn't have all the atts indicated by tupleDesc, read the
+	 * If tuple doesn't have all the atts indicated by attnum, read the
 	 * rest as NULLs or missing values
 	 */
 	if (attno < attnum)

src/backend/executor/execTuples.c

@@ -626,8 +626,7 @@ ExecCopySlotMinimalTuple(TupleTableSlot *slot)
 		return heap_copy_minimal_tuple(slot->tts_mintuple);
 	if (slot->tts_tuple)
 	{
-		if (TTS_HAS_PHYSICAL_TUPLE(slot) &&
-			HeapTupleHeaderGetNatts(slot->tts_tuple->t_data)
+		if (HeapTupleHeaderGetNatts(slot->tts_tuple->t_data)
 			< slot->tts_tupleDescriptor->natts)
 			return minimal_expand_tuple(slot->tts_tuple,
 										slot->tts_tupleDescriptor);
@@ -675,18 +674,15 @@ ExecFetchSlotTuple(TupleTableSlot *slot)
 		if (HeapTupleHeaderGetNatts(slot->tts_tuple->t_data) <
 			slot->tts_tupleDescriptor->natts)
 		{
+			HeapTuple tuple;
 			MemoryContext oldContext = MemoryContextSwitchTo(slot->tts_mcxt);
 
-			slot->tts_tuple = heap_expand_tuple(slot->tts_tuple,
-												slot->tts_tupleDescriptor);
-			slot->tts_shouldFree = true;
+			tuple = heap_expand_tuple(slot->tts_tuple,
+									  slot->tts_tupleDescriptor);
 			MemoryContextSwitchTo(oldContext);
-			return slot->tts_tuple;
-		}
-		else
-		{
-			return slot->tts_tuple;
+			slot = ExecStoreTuple(tuple, slot, InvalidBuffer, true);
 		}
+		return slot->tts_tuple;
 	}
 
 	/*