1 files changed, 166 insertions, 0 deletions

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 518d1df84a1..6a26fcef94c 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -19,15 +19,181 @@
  */
 #include "postgres.h"
 
+#include "access/heapam.h"
 #include "access/tableam.h"
+#include "storage/bufmgr.h"
 #include "utils/builtins.h"
 
 
 static const TableAmRoutine heapam_methods;
 
 
+/* ------------------------------------------------------------------------
+ * Slot related callbacks for heap AM
+ * ------------------------------------------------------------------------
+ */
+
+static const TupleTableSlotOps *
+heapam_slot_callbacks(Relation relation)
+{
+	return &TTSOpsBufferHeapTuple;
+}
+
+
+/* ------------------------------------------------------------------------
+ * Index Scan Callbacks for heap AM
+ * ------------------------------------------------------------------------
+ */
+
+static IndexFetchTableData *
+heapam_index_fetch_begin(Relation rel)
+{
+	IndexFetchHeapData *hscan = palloc0(sizeof(IndexFetchHeapData));
+
+	hscan->xs_base.rel = rel;
+	hscan->xs_cbuf = InvalidBuffer;
+
+	return &hscan->xs_base;
+}
+
+static void
+heapam_index_fetch_reset(IndexFetchTableData *scan)
+{
+	IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan;
+
+	if (BufferIsValid(hscan->xs_cbuf))
+	{
+		ReleaseBuffer(hscan->xs_cbuf);
+		hscan->xs_cbuf = InvalidBuffer;
+	}
+}
+
+static void
+heapam_index_fetch_end(IndexFetchTableData *scan)
+{
+	IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan;
+
+	heapam_index_fetch_reset(scan);
+
+	pfree(hscan);
+}
+
+static bool
+heapam_index_fetch_tuple(struct IndexFetchTableData *scan,
+						 ItemPointer tid,
+						 Snapshot snapshot,
+						 TupleTableSlot *slot,
+						 bool *call_again, bool *all_dead)
+{
+	IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan;
+	BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot;
+	bool		got_heap_tuple;
+
+	Assert(TTS_IS_BUFFERTUPLE(slot));
+
+	/* We can skip the buffer-switching logic if we're in mid-HOT chain. */
+	if (!*call_again)
+	{
+		/* Switch to correct buffer if we don't have it already */
+		Buffer		prev_buf = hscan->xs_cbuf;
+
+		hscan->xs_cbuf = ReleaseAndReadBuffer(hscan->xs_cbuf,
+											  hscan->xs_base.rel,
+											  ItemPointerGetBlockNumber(tid));
+
+		/*
+		 * Prune page, but only if we weren't already on this page
+		 */
+		if (prev_buf != hscan->xs_cbuf)
+			heap_page_prune_opt(hscan->xs_base.rel, hscan->xs_cbuf);
+	}
+
+	/* Obtain share-lock on the buffer so we can examine visibility */
+	LockBuffer(hscan->xs_cbuf, BUFFER_LOCK_SHARE);
+	got_heap_tuple = heap_hot_search_buffer(tid,
+											hscan->xs_base.rel,
+											hscan->xs_cbuf,
+											snapshot,
+											&bslot->base.tupdata,
+											all_dead,
+											!*call_again);
+	bslot->base.tupdata.t_self = *tid;
+	LockBuffer(hscan->xs_cbuf, BUFFER_LOCK_UNLOCK);
+
+	if (got_heap_tuple)
+	{
+		/*
+		 * Only in a non-MVCC snapshot can more than one member of the HOT
+		 * chain be visible.
+		 */
+		*call_again = !IsMVCCSnapshot(snapshot);
+
+		slot->tts_tableOid = RelationGetRelid(scan->rel);
+		ExecStoreBufferHeapTuple(&bslot->base.tupdata, slot, hscan->xs_cbuf);
+	}
+	else
+	{
+		/* We've reached the end of the HOT chain. */
+		*call_again = false;
+	}
+
+	return got_heap_tuple;
+}
+
+
+/* ------------------------------------------------------------------------
+ * Callbacks for non-modifying operations on individual tuples for heap AM
+ * ------------------------------------------------------------------------
+ */
+
+static bool
+heapam_tuple_satisfies_snapshot(Relation rel, TupleTableSlot *slot,
+								Snapshot snapshot)
+{
+	BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot;
+	bool		res;
+
+	Assert(TTS_IS_BUFFERTUPLE(slot));
+	Assert(BufferIsValid(bslot->buffer));
+
+	/*
+	 * We need buffer pin and lock to call HeapTupleSatisfiesVisibility.
+	 * Caller should be holding pin, but not lock.
+	 */
+	LockBuffer(bslot->buffer, BUFFER_LOCK_SHARE);
+	res = HeapTupleSatisfiesVisibility(bslot->base.tuple, snapshot,
+									   bslot->buffer);
+	LockBuffer(bslot->buffer, BUFFER_LOCK_UNLOCK);
+
+	return res;
+}
+
+
+/* ------------------------------------------------------------------------
+ * Definition of the heap table access method.
+ * ------------------------------------------------------------------------
+ */
+
 static const TableAmRoutine heapam_methods = {
 	.type = T_TableAmRoutine,
+
+	.slot_callbacks = heapam_slot_callbacks,
+
+	.scan_begin = heap_beginscan,
+	.scan_end = heap_endscan,
+	.scan_rescan = heap_rescan,
+	.scan_getnextslot = heap_getnextslot,
+
+	.parallelscan_estimate = table_block_parallelscan_estimate,
+	.parallelscan_initialize = table_block_parallelscan_initialize,
+	.parallelscan_reinitialize = table_block_parallelscan_reinitialize,
+
+	.index_fetch_begin = heapam_index_fetch_begin,
+	.index_fetch_reset = heapam_index_fetch_reset,
+	.index_fetch_end = heapam_index_fetch_end,
+	.index_fetch_tuple = heapam_index_fetch_tuple,
+
+	.tuple_satisfies_snapshot = heapam_tuple_satisfies_snapshot,
 };