Remove dependency on HeapTuple from predicate locking functions.

The following changes make the predicate locking functions more
generic and suitable for use by future access methods:

- PredicateLockTuple() is renamed to PredicateLockTID().  It takes
  ItemPointer and inserting transaction ID instead of HeapTuple.

- CheckForSerializableConflictIn() takes blocknum instead of buffer.

- CheckForSerializableConflictOut() no longer takes HeapTuple or buffer.

Author: Ashwin Agrawal
Reviewed-by: Andres Freund, Kuntal Ghosh, Thomas Munro
Discussion: https://postgr.es/m/CALfoeiv0k3hkEb3Oqk%3DziWqtyk2Jys1UOK5hwRBNeANT_yX%2Bng%40mail.gmail.com

src/backend/access/gin/ginbtree.c

@@ -89,7 +89,7 @@ ginFindLeafPage(GinBtree btree, bool searchMode,
 	stack->predictNumber = 1;
 
 	if (rootConflictCheck)
-		CheckForSerializableConflictIn(btree->index, NULL, stack->buffer);
+		CheckForSerializableConflictIn(btree->index, NULL, btree->rootBlkno);
 
 	for (;;)
 	{

src/backend/access/gin/ginfast.c

@@ -246,7 +246,7 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector)
 	 * tree, so it conflicts with all serializable scans.  All scans acquire a
 	 * predicate lock on the metabuffer to represent that.
 	 */
-	CheckForSerializableConflictIn(index, NULL, metabuffer);
+	CheckForSerializableConflictIn(index, NULL, GIN_METAPAGE_BLKNO);
 
 	if (collector->sumsize + collector->ntuples * sizeof(ItemIdData) > GinListPageSize)
 	{

src/backend/access/gin/gininsert.c

@@ -216,7 +216,8 @@ ginEntryInsert(GinState *ginstate,
 			return;
 		}
 
-		CheckForSerializableConflictIn(ginstate->index, NULL, stack->buffer);
+		CheckForSerializableConflictIn(ginstate->index, NULL,
+									   BufferGetBlockNumber(stack->buffer));
 		/* modify an existing leaf entry */
 		itup = addItemPointersToLeafTuple(ginstate, itup,
 										  items, nitem, buildStats, stack->buffer);
@@ -225,7 +226,8 @@ ginEntryInsert(GinState *ginstate,
 	}
 	else
 	{
-		CheckForSerializableConflictIn(ginstate->index, NULL, stack->buffer);
+		CheckForSerializableConflictIn(ginstate->index, NULL,
+									   BufferGetBlockNumber(stack->buffer));
 		/* no match, so construct a new leaf entry */
 		itup = buildFreshLeafTuple(ginstate, attnum, key, category,
 								   items, nitem, buildStats, stack->buffer);

src/backend/access/gist/gist.c

@@ -1264,7 +1264,7 @@ gistinserttuples(GISTInsertState *state, GISTInsertStack *stack,
 	 * Check for any rw conflicts (in serializable isolation level) just
 	 * before we intend to modify the page
 	 */
-	CheckForSerializableConflictIn(state->r, NULL, stack->buffer);
+	CheckForSerializableConflictIn(state->r, NULL, BufferGetBlockNumber(stack->buffer));
 
 	/* Insert the tuple(s) to the page, splitting the page if necessary */
 	is_split = gistplacetopage(state->r, state->freespace, giststate,

src/backend/access/hash/hashinsert.c

@@ -88,7 +88,7 @@ restart_insert:
 										  &usedmetap);
 	Assert(usedmetap != NULL);
 
-	CheckForSerializableConflictIn(rel, NULL, buf);
+	CheckForSerializableConflictIn(rel, NULL, BufferGetBlockNumber(buf));
 
 	/* remember the primary bucket buffer to release the pin on it at end. */
 	bucket_buf = buf;

src/backend/access/heap/heapam.c

@@ -41,6 +41,7 @@
 #include "access/multixact.h"
 #include "access/parallel.h"
 #include "access/relscan.h"
+#include "access/subtrans.h"
 #include "access/sysattr.h"
 #include "access/tableam.h"
 #include "access/transam.h"
@@ -446,8 +447,8 @@ heapgetpage(TableScanDesc sscan, BlockNumber page)
 			else
 				valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer);
 
-			CheckForSerializableConflictOut(valid, scan->rs_base.rs_rd,
-											&loctup, buffer, snapshot);
+			HeapCheckForSerializableConflictOut(valid, scan->rs_base.rs_rd,
+												&loctup, buffer, snapshot);
 
 			if (valid)
 				scan->rs_vistuples[ntup++] = lineoff;
@@ -668,9 +669,9 @@ heapgettup(HeapScanDesc scan,
 													 snapshot,
 													 scan->rs_cbuf);
 
-				CheckForSerializableConflictOut(valid, scan->rs_base.rs_rd,
-												tuple, scan->rs_cbuf,
-												snapshot);
+				HeapCheckForSerializableConflictOut(valid, scan->rs_base.rs_rd,
+													tuple, scan->rs_cbuf,
+													snapshot);
 
 				if (valid && key != NULL)
 					HeapKeyTest(tuple, RelationGetDescr(scan->rs_base.rs_rd),
@@ -1477,9 +1478,10 @@ heap_fetch(Relation relation,
 	valid = HeapTupleSatisfiesVisibility(tuple, snapshot, buffer);
 
 	if (valid)
-		PredicateLockTuple(relation, tuple, snapshot);
+		PredicateLockTID(relation, &(tuple->t_self), snapshot,
+						 HeapTupleHeaderGetXmin(tuple->t_data));
 
-	CheckForSerializableConflictOut(valid, relation, tuple, buffer, snapshot);
+	HeapCheckForSerializableConflictOut(valid, relation, tuple, buffer, snapshot);
 
 	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
 
@@ -1610,13 +1612,14 @@ heap_hot_search_buffer(ItemPointer tid, Relation relation, Buffer buffer,
 		{
 			/* If it's visible per the snapshot, we must return it */
 			valid = HeapTupleSatisfiesVisibility(heapTuple, snapshot, buffer);
-			CheckForSerializableConflictOut(valid, relation, heapTuple,
-											buffer, snapshot);
+			HeapCheckForSerializableConflictOut(valid, relation, heapTuple,
+												buffer, snapshot);
 
 			if (valid)
 			{
 				ItemPointerSetOffsetNumber(tid, offnum);
-				PredicateLockTuple(relation, heapTuple, snapshot);
+				PredicateLockTID(relation, &heapTuple->t_self, snapshot,
+								 HeapTupleHeaderGetXmin(heapTuple->t_data));
 				if (all_dead)
 					*all_dead = false;
 				return true;
@@ -1750,7 +1753,7 @@ heap_get_latest_tid(TableScanDesc sscan,
 		 * candidate.
 		 */
 		valid = HeapTupleSatisfiesVisibility(&tp, snapshot, buffer);
-		CheckForSerializableConflictOut(valid, relation, &tp, buffer, snapshot);
+		HeapCheckForSerializableConflictOut(valid, relation, &tp, buffer, snapshot);
 		if (valid)
 			*tid = ctid;
 
@@ -1905,7 +1908,7 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
 	 * lock "gaps" as index page locks do.  So we don't need to specify a
 	 * buffer when making the call, which makes for a faster check.
 	 */
-	CheckForSerializableConflictIn(relation, NULL, InvalidBuffer);
+	CheckForSerializableConflictIn(relation, NULL, InvalidBlockNumber);
 
 	/* NO EREPORT(ERROR) from here till changes are logged */
 	START_CRIT_SECTION();
@@ -2159,7 +2162,7 @@ heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
 	 * lock "gaps" as index page locks do.  So we don't need to specify a
 	 * buffer when making the call, which makes for a faster check.
 	 */
-	CheckForSerializableConflictIn(relation, NULL, InvalidBuffer);
+	CheckForSerializableConflictIn(relation, NULL, InvalidBlockNumber);
 
 	ndone = 0;
 	while (ndone < ntuples)
@@ -2350,7 +2353,7 @@ heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
 	 * lock "gaps" as index page locks do.  So we don't need to specify a
 	 * buffer when making the call.
 	 */
-	CheckForSerializableConflictIn(relation, NULL, InvalidBuffer);
+	CheckForSerializableConflictIn(relation, NULL, InvalidBlockNumber);
 
 	/*
 	 * If tuples are cachable, mark them for invalidation from the caches in
@@ -2664,7 +2667,7 @@ l1:
 	 * being visible to the scan (i.e., an exclusive buffer content lock is
 	 * continuously held from this point until the tuple delete is visible).
 	 */
-	CheckForSerializableConflictIn(relation, &tp, buffer);
+	CheckForSerializableConflictIn(relation, tid, BufferGetBlockNumber(buffer));
 
 	/* replace cid with a combo cid if necessary */
 	HeapTupleHeaderAdjustCmax(tp.t_data, &cid, &iscombo);
@@ -3580,7 +3583,7 @@ l2:
 	 * will include checking the relation level, there is no benefit to a
 	 * separate check for the new tuple.
 	 */
-	CheckForSerializableConflictIn(relation, &oldtup, buffer);
+	CheckForSerializableConflictIn(relation, otid, BufferGetBlockNumber(buffer));
 
 	/*
 	 * At this point newbuf and buffer are both pinned and locked, and newbuf
@@ -9043,3 +9046,93 @@ heap_mask(char *pagedata, BlockNumber blkno)
 		}
 	}
 }
+
+/*
+ * HeapCheckForSerializableConflictOut
+ *		We are reading a tuple which has been modified.  If it is visible to
+ *		us but has been deleted, that indicates a rw-conflict out.  If it's
+ *		not visible and was created by a concurrent (overlapping)
+ *		serializable transaction, that is also a rw-conflict out,
+ *
+ * We will determine the top level xid of the writing transaction with which
+ * we may be in conflict, and check for overlap with our own transaction.
+ * If the transactions overlap (i.e., they cannot see each other's writes),
+ * then we have a conflict out.
+ *
+ * This function should be called just about anywhere in heapam.c where a
+ * tuple has been read. The caller must hold at least a shared lock on the
+ * buffer, because this function might set hint bits on the tuple. There is
+ * currently no known reason to call this function from an index AM.
+ */
+void
+HeapCheckForSerializableConflictOut(bool visible, Relation relation,
+									HeapTuple tuple, Buffer buffer,
+									Snapshot snapshot)
+{
+	TransactionId xid;
+	HTSV_Result htsvResult;
+
+	if (!CheckForSerializableConflictOutNeeded(relation, snapshot))
+		return;
+
+	/*
+	 * Check to see whether the tuple has been written to by a concurrent
+	 * transaction, either to create it not visible to us, or to delete it
+	 * while it is visible to us.  The "visible" bool indicates whether the
+	 * tuple is visible to us, while HeapTupleSatisfiesVacuum checks what else
+	 * is going on with it.
+	 */
+	htsvResult = HeapTupleSatisfiesVacuum(tuple, TransactionXmin, buffer);
+	switch (htsvResult)
+	{
+		case HEAPTUPLE_LIVE:
+			if (visible)
+				return;
+			xid = HeapTupleHeaderGetXmin(tuple->t_data);
+			break;
+		case HEAPTUPLE_RECENTLY_DEAD:
+			if (!visible)
+				return;
+			xid = HeapTupleHeaderGetUpdateXid(tuple->t_data);
+			break;
+		case HEAPTUPLE_DELETE_IN_PROGRESS:
+			xid = HeapTupleHeaderGetUpdateXid(tuple->t_data);
+			break;
+		case HEAPTUPLE_INSERT_IN_PROGRESS:
+			xid = HeapTupleHeaderGetXmin(tuple->t_data);
+			break;
+		case HEAPTUPLE_DEAD:
+			return;
+		default:
+
+			/*
+			 * The only way to get to this default clause is if a new value is
+			 * added to the enum type without adding it to this switch
+			 * statement.  That's a bug, so elog.
+			 */
+			elog(ERROR, "unrecognized return value from HeapTupleSatisfiesVacuum: %u", htsvResult);
+
+			/*
+			 * In spite of having all enum values covered and calling elog on
+			 * this default, some compilers think this is a code path which
+			 * allows xid to be used below without initialization. Silence
+			 * that warning.
+			 */
+			xid = InvalidTransactionId;
+	}
+
+	Assert(TransactionIdIsValid(xid));
+	Assert(TransactionIdFollowsOrEquals(xid, TransactionXmin));
+
+	/*
+	 * Find top level xid.  Bail out if xid is too early to be a conflict, or
+	 * if it's our own xid.
+	 */
+	if (TransactionIdEquals(xid, GetTopTransactionIdIfAny()))
+		return;
+	xid = SubTransGetTopmostTransaction(xid);
+	if (TransactionIdPrecedes(xid, TransactionXmin))
+		return;
+
+	return CheckForSerializableConflictOut(relation, xid, snapshot);
+}

src/backend/access/heap/heapam_handler.c

@@ -2171,10 +2171,11 @@ heapam_scan_bitmap_next_block(TableScanDesc scan,
 			if (valid)
 			{
 				hscan->rs_vistuples[ntup++] = offnum;
-				PredicateLockTuple(scan->rs_rd, &loctup, snapshot);
+				PredicateLockTID(scan->rs_rd, &loctup.t_self, snapshot,
+								 HeapTupleHeaderGetXmin(loctup.t_data));
 			}
-			CheckForSerializableConflictOut(valid, scan->rs_rd, &loctup,
-											buffer, snapshot);
+			HeapCheckForSerializableConflictOut(valid, scan->rs_rd, &loctup,
+												buffer, snapshot);
 		}
 	}
 
@@ -2361,8 +2362,8 @@ heapam_scan_sample_next_tuple(TableScanDesc scan, SampleScanState *scanstate,
 
 			/* in pagemode, heapgetpage did this for us */
 			if (!pagemode)
-				CheckForSerializableConflictOut(visible, scan->rs_rd, tuple,
-												hscan->rs_cbuf, scan->rs_snapshot);
+				HeapCheckForSerializableConflictOut(visible, scan->rs_rd, tuple,
+													hscan->rs_cbuf, scan->rs_snapshot);
 
 			/* Try next tuple from same page. */
 			if (!visible)

src/backend/access/index/indexam.c

@@ -180,8 +180,8 @@ index_insert(Relation indexRelation,
 
 	if (!(indexRelation->rd_indam->ampredlocks))
 		CheckForSerializableConflictIn(indexRelation,
-									   (HeapTuple) NULL,
-									   InvalidBuffer);
+									   (ItemPointer) NULL,
+									   InvalidBlockNumber);
 
 	return indexRelation->rd_indam->aminsert(indexRelation, values, isnull,
 											 heap_t_ctid, heapRelation,

src/backend/access/nbtree/nbtinsert.c

@@ -285,7 +285,7 @@ top:
 		 * checkingunique and !heapkeyspace cases, but it's okay to use the
 		 * first page the value could be on (with scantid omitted) instead.
 		 */
-		CheckForSerializableConflictIn(rel, NULL, insertstate.buf);
+		CheckForSerializableConflictIn(rel, NULL, BufferGetBlockNumber(insertstate.buf));
 
 		/*
 		 * Do the insertion.  Note that insertstate contains cached binary
@@ -528,7 +528,7 @@ _bt_check_unique(Relation rel, BTInsertState insertstate, Relation heapRel,
 					 * otherwise be masked by this unique constraint
 					 * violation.
 					 */
-					CheckForSerializableConflictIn(rel, NULL, insertstate->buf);
+					CheckForSerializableConflictIn(rel, NULL, BufferGetBlockNumber(insertstate->buf));
 
 					/*
 					 * This is a definite conflict.  Break the tuple down into

src/backend/storage/lmgr/predicate.c

@@ -163,8 +163,8 @@
  *		PredicateLockRelation(Relation relation, Snapshot snapshot)
  *		PredicateLockPage(Relation relation, BlockNumber blkno,
  *						Snapshot snapshot)
- *		PredicateLockTuple(Relation relation, HeapTuple tuple,
- *						Snapshot snapshot)
+ *		PredicateLockTID(Relation relation, ItemPointer tid, Snapshot snapshot,
+ *						 TransactionId insert_xid)
  *		PredicateLockPageSplit(Relation relation, BlockNumber oldblkno,
  *							   BlockNumber newblkno)
  *		PredicateLockPageCombine(Relation relation, BlockNumber oldblkno,
@@ -173,11 +173,10 @@
  *		ReleasePredicateLocks(bool isCommit, bool isReadOnlySafe)
  *
  * conflict detection (may also trigger rollback)
- *		CheckForSerializableConflictOut(bool visible, Relation relation,
- *										HeapTupleData *tup, Buffer buffer,
+ *		CheckForSerializableConflictOut(Relation relation, TransactionId xid,
  *										Snapshot snapshot)
- *		CheckForSerializableConflictIn(Relation relation, HeapTupleData *tup,
- *									   Buffer buffer)
+ *		CheckForSerializableConflictIn(Relation relation, ItemPointer tid,
+ *									   BlockNumber blkno)
  *		CheckTableForSerializableConflictIn(Relation relation)
  *
  * final rollback checking
@@ -193,8 +192,6 @@
 
 #include "postgres.h"
 
-#include "access/heapam.h"
-#include "access/htup_details.h"
 #include "access/parallel.h"
 #include "access/slru.h"
 #include "access/subtrans.h"
@@ -2538,28 +2535,28 @@ PredicateLockPage(Relation relation, BlockNumber blkno, Snapshot snapshot)
 }
 
 /*
- *		PredicateLockTuple
+ *		PredicateLockTID
  *
  * Gets a predicate lock at the tuple level.
  * Skip if not in full serializable transaction isolation level.
  * Skip if this is a temporary table.
  */
 void
-PredicateLockTuple(Relation relation, HeapTuple tuple, Snapshot snapshot)
+PredicateLockTID(Relation relation, ItemPointer tid, Snapshot snapshot,
+				 TransactionId tuple_xid)
 {
 	PREDICATELOCKTARGETTAG tag;
-	ItemPointer tid;
 
 	if (!SerializationNeededForRead(relation, snapshot))
 		return;
 
 	/*
-	 * If it's a heap tuple, return if this xact wrote it.
+	 * Return if this xact wrote it.
 	 */
 	if (relation->rd_index == NULL)
 	{
 		/* If we wrote it; we already have a write lock. */
-		if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple->t_data)))
+		if (TransactionIdIsCurrentTransactionId(tuple_xid))
 			return;
 	}
 
@@ -2575,7 +2572,6 @@ PredicateLockTuple(Relation relation, HeapTuple tuple, Snapshot snapshot)
 	if (PredicateLockExists(&tag))
 		return;
 
-	tid = &(tuple->t_self);
 	SET_PREDICATELOCKTARGETTAG_TUPLE(tag,
 									 relation->rd_node.dbNode,
 									 relation->rd_id,
@@ -4020,33 +4016,41 @@ XidIsConcurrent(TransactionId xid)
 	return false;
 }
 
+bool
+CheckForSerializableConflictOutNeeded(Relation relation, Snapshot snapshot)
+{
+	if (!SerializationNeededForRead(relation, snapshot))
+		return false;
+
+	/* Check if someone else has already decided that we need to die */
+	if (SxactIsDoomed(MySerializableXact))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("could not serialize access due to read/write dependencies among transactions"),
+				 errdetail_internal("Reason code: Canceled on identification as a pivot, during conflict out checking."),
+				 errhint("The transaction might succeed if retried.")));
+	}
+
+	return true;
+}
+
 /*
  * CheckForSerializableConflictOut
- *		We are reading a tuple which has been modified.  If it is visible to
- *		us but has been deleted, that indicates a rw-conflict out.  If it's
- *		not visible and was created by a concurrent (overlapping)
- *		serializable transaction, that is also a rw-conflict out,
+ *		A table AM is reading a tuple that has been modified.  After determining
+ *		that it is visible to us, it should call this function with the top
+ *		level xid of the writing transaction.
  *
- * We will determine the top level xid of the writing transaction with which
- * we may be in conflict, and check for overlap with our own transaction.
- * If the transactions overlap (i.e., they cannot see each other's writes),
- * then we have a conflict out.
- *
- * This function should be called just about anywhere in heapam.c where a
- * tuple has been read. The caller must hold at least a shared lock on the
- * buffer, because this function might set hint bits on the tuple. There is
- * currently no known reason to call this function from an index AM.
+ * This function will check for overlap with our own transaction.  If the
+ * transactions overlap (i.e., they cannot see each other's writes), then we
+ * have a conflict out.
  */
 void
-CheckForSerializableConflictOut(bool visible, Relation relation,
-								HeapTuple tuple, Buffer buffer,
-								Snapshot snapshot)
+CheckForSerializableConflictOut(Relation relation, TransactionId xid, Snapshot snapshot)
 {
-	TransactionId xid;
 	SERIALIZABLEXIDTAG sxidtag;
 	SERIALIZABLEXID *sxid;
 	SERIALIZABLEXACT *sxact;
-	HTSV_Result htsvResult;
 
 	if (!SerializationNeededForRead(relation, snapshot))
 		return;
@@ -4060,64 +4064,8 @@ CheckForSerializableConflictOut(bool visible, Relation relation,
 				 errdetail_internal("Reason code: Canceled on identification as a pivot, during conflict out checking."),
 				 errhint("The transaction might succeed if retried.")));
 	}
-
-	/*
-	 * Check to see whether the tuple has been written to by a concurrent
-	 * transaction, either to create it not visible to us, or to delete it
-	 * while it is visible to us.  The "visible" bool indicates whether the
-	 * tuple is visible to us, while HeapTupleSatisfiesVacuum checks what else
-	 * is going on with it.
-	 */
-	htsvResult = HeapTupleSatisfiesVacuum(tuple, TransactionXmin, buffer);
-	switch (htsvResult)
-	{
-		case HEAPTUPLE_LIVE:
-			if (visible)
-				return;
-			xid = HeapTupleHeaderGetXmin(tuple->t_data);
-			break;
-		case HEAPTUPLE_RECENTLY_DEAD:
-			if (!visible)
-				return;
-			xid = HeapTupleHeaderGetUpdateXid(tuple->t_data);
-			break;
-		case HEAPTUPLE_DELETE_IN_PROGRESS:
-			xid = HeapTupleHeaderGetUpdateXid(tuple->t_data);
-			break;
-		case HEAPTUPLE_INSERT_IN_PROGRESS:
-			xid = HeapTupleHeaderGetXmin(tuple->t_data);
-			break;
-		case HEAPTUPLE_DEAD:
-			return;
-		default:
-
-			/*
-			 * The only way to get to this default clause is if a new value is
-			 * added to the enum type without adding it to this switch
-			 * statement.  That's a bug, so elog.
-			 */
-			elog(ERROR, "unrecognized return value from HeapTupleSatisfiesVacuum: %u", htsvResult);
-
-			/*
-			 * In spite of having all enum values covered and calling elog on
-			 * this default, some compilers think this is a code path which
-			 * allows xid to be used below without initialization. Silence
-			 * that warning.
-			 */
-			xid = InvalidTransactionId;
-	}
 	Assert(TransactionIdIsValid(xid));
-	Assert(TransactionIdFollowsOrEquals(xid, TransactionXmin));
 
-	/*
-	 * Find top level xid.  Bail out if xid is too early to be a conflict, or
-	 * if it's our own xid.
-	 */
-	if (TransactionIdEquals(xid, GetTopTransactionIdIfAny()))
-		return;
-	xid = SubTransGetTopmostTransaction(xid);
-	if (TransactionIdPrecedes(xid, TransactionXmin))
-		return;
 	if (TransactionIdEquals(xid, GetTopTransactionIdIfAny()))
 		return;
 
@@ -4423,8 +4371,7 @@ CheckTargetForConflictsIn(PREDICATELOCKTARGETTAG *targettag)
  * tuple itself.
  */
 void
-CheckForSerializableConflictIn(Relation relation, HeapTuple tuple,
-							   Buffer buffer)
+CheckForSerializableConflictIn(Relation relation, ItemPointer tid, BlockNumber blkno)
 {
 	PREDICATELOCKTARGETTAG targettag;
 
@@ -4454,22 +4401,22 @@ CheckForSerializableConflictIn(Relation relation, HeapTuple tuple,
 	 * It is not possible to take and hold a lock across the checks for all
 	 * granularities because each target could be in a separate partition.
 	 */
-	if (tuple != NULL)
+	if (tid != NULL)
 	{
 		SET_PREDICATELOCKTARGETTAG_TUPLE(targettag,
 										 relation->rd_node.dbNode,
 										 relation->rd_id,
-										 ItemPointerGetBlockNumber(&(tuple->t_self)),
-										 ItemPointerGetOffsetNumber(&(tuple->t_self)));
+										 ItemPointerGetBlockNumber(tid),
+										 ItemPointerGetOffsetNumber(tid));
 		CheckTargetForConflictsIn(&targettag);
 	}
 
-	if (BufferIsValid(buffer))
+	if (blkno != InvalidBlockNumber)
 	{
 		SET_PREDICATELOCKTARGETTAG_PAGE(targettag,
 										relation->rd_node.dbNode,
 										relation->rd_id,
-										BufferGetBlockNumber(buffer));
+										blkno);
 		CheckTargetForConflictsIn(&targettag);
 	}
 

src/include/access/heapam.h

@@ -220,5 +220,7 @@ extern bool ResolveCminCmaxDuringDecoding(struct HTAB *tuplecid_data,
 										  HeapTuple htup,
 										  Buffer buffer,
 										  CommandId *cmin, CommandId *cmax);
+extern void HeapCheckForSerializableConflictOut(bool valid, Relation relation, HeapTuple tuple,
+												Buffer buffer, Snapshot snapshot);
 
 #endif							/* HEAPAM_H */

src/include/storage/predicate.h

@@ -57,16 +57,17 @@ extern void SetSerializableTransactionSnapshot(Snapshot snapshot,
 extern void RegisterPredicateLockingXid(TransactionId xid);
 extern void PredicateLockRelation(Relation relation, Snapshot snapshot);
 extern void PredicateLockPage(Relation relation, BlockNumber blkno, Snapshot snapshot);
-extern void PredicateLockTuple(Relation relation, HeapTuple tuple, Snapshot snapshot);
+extern void PredicateLockTID(Relation relation, ItemPointer tid, Snapshot snapshot,
+							 TransactionId insert_xid);
 extern void PredicateLockPageSplit(Relation relation, BlockNumber oldblkno, BlockNumber newblkno);
 extern void PredicateLockPageCombine(Relation relation, BlockNumber oldblkno, BlockNumber newblkno);
 extern void TransferPredicateLocksToHeapRelation(Relation relation);
 extern void ReleasePredicateLocks(bool isCommit, bool isReadOnlySafe);
 
 /* conflict detection (may also trigger rollback) */
-extern void CheckForSerializableConflictOut(bool valid, Relation relation, HeapTuple tuple,
-											Buffer buffer, Snapshot snapshot);
-extern void CheckForSerializableConflictIn(Relation relation, HeapTuple tuple, Buffer buffer);
+extern bool CheckForSerializableConflictOutNeeded(Relation relation, Snapshot snapshot);
+extern void CheckForSerializableConflictOut(Relation relation, TransactionId xid, Snapshot snapshot);
+extern void CheckForSerializableConflictIn(Relation relation, ItemPointer tid, BlockNumber blkno);
 extern void CheckTableForSerializableConflictIn(Relation relation);
 
 /* final rollback checking */