Remove nbtree BTreeTupleSetAltHeapTID() function.

Since heap TID is supposed to be just another key attribute to the
implementation, it doesn't make much sense to have separate
BTreeTupleSetNAtts() and BTreeTupleSetAltHeapTID() functions.  Merge the
two functions together.  This slightly simplifies _bt_truncate().

4 files changed, 26 insertions, 28 deletions

diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index 1675298f73d..cbd4ec3b39e 100644
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -2413,7 +2413,7 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
 	left_item = (IndexTuple) palloc(left_item_sz);
 	left_item->t_info = left_item_sz;
 	BTreeTupleSetDownLink(left_item, lbkno);
-	BTreeTupleSetNAtts(left_item, 0);
+	BTreeTupleSetNAtts(left_item, 0, false);
 
 	/*
 	 * Create downlink item for right page.  The key for it is obtained from
@@ -2571,7 +2571,7 @@ _bt_pgaddtup(Page page,
 	{
 		trunctuple = *itup;
 		trunctuple.t_info = sizeof(IndexTupleData);
-		BTreeTupleSetNAtts(&trunctuple, 0);
+		BTreeTupleSetNAtts(&trunctuple, 0, false);
 		itup = &trunctuple;
 		itemsize = sizeof(IndexTupleData);
 	}
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index 29a6f5ade61..9d249f7a6b6 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -771,7 +771,7 @@ _bt_sortaddtup(Page page,
 	{
 		trunctuple = *itup;
 		trunctuple.t_info = sizeof(IndexTupleData);
-		BTreeTupleSetNAtts(&trunctuple, 0);
+		BTreeTupleSetNAtts(&trunctuple, 0, false);
 		itup = &trunctuple;
 		itemsize = sizeof(IndexTupleData);
 	}
@@ -1045,7 +1045,7 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup,
 		Assert(state->btps_lowkey == NULL);
 		state->btps_lowkey = palloc0(sizeof(IndexTupleData));
 		state->btps_lowkey->t_info = sizeof(IndexTupleData);
-		BTreeTupleSetNAtts(state->btps_lowkey, 0);
+		BTreeTupleSetNAtts(state->btps_lowkey, 0, false);
 	}
 
 	/*
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 86cec248593..08d7201f196 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -2239,7 +2239,7 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
 	 */
 	if (keepnatts <= nkeyatts)
 	{
-		BTreeTupleSetNAtts(pivot, keepnatts);
+		BTreeTupleSetNAtts(pivot, keepnatts, false);
 		return pivot;
 	}
 
@@ -2262,11 +2262,13 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
 	/* Cannot leak memory here */
 	pfree(pivot);
 
-	/* Store heap TID in enlarged pivot tuple */
+	/*
+	 * Store all of firstright's key attribute values plus a tiebreaker heap
+	 * TID value in enlarged pivot tuple
+	 */
 	tidpivot->t_info &= ~INDEX_SIZE_MASK;
 	tidpivot->t_info |= newsize;
-	BTreeTupleSetNAtts(tidpivot, nkeyatts);
-	BTreeTupleSetAltHeapTID(tidpivot);
+	BTreeTupleSetNAtts(tidpivot, nkeyatts, true);
 	pivotheaptid = BTreeTupleGetHeapTID(tidpivot);
 
 	/*
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 5f67fc04e09..072a41ef8bf 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -460,32 +460,28 @@ BTreeTupleSetDownLink(IndexTuple pivot, BlockNumber blkno)
 	)
 
 /*
- * Set number of attributes in tuple, making it into a pivot tuple
+ * Set number of key attributes in tuple.
+ *
+ * The heap TID tiebreaker attribute bit may also be set here, indicating that
+ * a heap TID value will be stored at the end of the tuple (i.e. using the
+ * special pivot tuple representation).
  */
 static inline void
-BTreeTupleSetNAtts(IndexTuple itup, int natts)
+BTreeTupleSetNAtts(IndexTuple itup, uint16 nkeyatts, bool heaptid)
 {
-	Assert(natts <= INDEX_MAX_KEYS);
+	Assert(nkeyatts <= INDEX_MAX_KEYS);
+	Assert((nkeyatts & BT_RESERVED_OFFSET_MASK) == 0);
+	Assert(!heaptid || nkeyatts > 0);
+	Assert(!BTreeTupleIsPivot(itup) || nkeyatts == 0);
 
 	itup->t_info |= INDEX_ALT_TID_MASK;
-	/* BT_IS_POSTING bit may be unset -- tuple always becomes a pivot tuple */
-	ItemPointerSetOffsetNumber(&itup->t_tid, natts);
-	Assert(BTreeTupleIsPivot(itup));
-}
-
-/*
- * Set the bit indicating heap TID attribute present in pivot tuple
- */
-static inline void
-BTreeTupleSetAltHeapTID(IndexTuple pivot)
-{
-	OffsetNumber existing;
 
-	Assert(BTreeTupleIsPivot(pivot));
+	if (heaptid)
+		nkeyatts |= BT_PIVOT_HEAP_TID_ATTR;
 
-	existing = ItemPointerGetOffsetNumberNoCheck(&pivot->t_tid);
-	ItemPointerSetOffsetNumber(&pivot->t_tid,
-							   existing | BT_PIVOT_HEAP_TID_ATTR);
+	/* BT_IS_POSTING bit is deliberately unset here */
+	ItemPointerSetOffsetNumber(&itup->t_tid, nkeyatts);
+	Assert(BTreeTupleIsPivot(itup));
 }
 
 /*
@@ -505,7 +501,7 @@ static inline void
 BTreeTupleSetTopParent(IndexTuple leafhikey, BlockNumber blkno)
 {
 	ItemPointerSetBlockNumber(&leafhikey->t_tid, blkno);
-	BTreeTupleSetNAtts(leafhikey, 0);
+	BTreeTupleSetNAtts(leafhikey, 0, false);
 }
 
 /*