4 files changed, 13 insertions, 129 deletions
diff --git a/src/backend/executor/execAmi.c b/src/backend/executor/execAmi.c
index 643aaace3a9..7027d7f8051 100644
--- a/src/backend/executor/execAmi.c
+++ b/src/backend/executor/execAmi.c
@@ -271,16 +271,20 @@ ExecReScan(PlanState *node)
  * ExecMarkPos
  *
  * Marks the current scan position.
+ *
+ * NOTE: mark/restore capability is currently needed only for plan nodes
+ * that are the immediate inner child of a MergeJoin node.  Since MergeJoin
+ * requires sorted input, there is never any need to support mark/restore in
+ * node types that cannot produce sorted output.  There are some cases in
+ * which a node can pass through sorted data from its child; if we don't
+ * implement mark/restore for such a node type, the planner compensates by
+ * inserting a Material node above that node.
  */
 void
 ExecMarkPos(PlanState *node)
 {
 	switch (nodeTag(node))
 	{
-		case T_SeqScanState:
-			ExecSeqMarkPos((SeqScanState *) node);
-			break;
-
 		case T_IndexScanState:
 			ExecIndexMarkPos((IndexScanState *) node);
 			break;
@@ -289,14 +293,6 @@ ExecMarkPos(PlanState *node)
 			ExecIndexOnlyMarkPos((IndexOnlyScanState *) node);
 			break;
 
-		case T_TidScanState:
-			ExecTidMarkPos((TidScanState *) node);
-			break;
-
-		case T_ValuesScanState:
-			ExecValuesMarkPos((ValuesScanState *) node);
-			break;
-
 		case T_CustomScanState:
 			ExecCustomMarkPos((CustomScanState *) node);
 			break;
@@ -338,10 +334,6 @@ ExecRestrPos(PlanState *node)
 {
 	switch (nodeTag(node))
 	{
-		case T_SeqScanState:
-			ExecSeqRestrPos((SeqScanState *) node);
-			break;
-
 		case T_IndexScanState:
 			ExecIndexRestrPos((IndexScanState *) node);
 			break;
@@ -350,14 +342,6 @@ ExecRestrPos(PlanState *node)
 			ExecIndexOnlyRestrPos((IndexOnlyScanState *) node);
 			break;
 
-		case T_TidScanState:
-			ExecTidRestrPos((TidScanState *) node);
-			break;
-
-		case T_ValuesScanState:
-			ExecValuesRestrPos((ValuesScanState *) node);
-			break;
-
 		case T_CustomScanState:
 			ExecCustomRestrPos((CustomScanState *) node);
 			break;
@@ -386,14 +370,6 @@ ExecRestrPos(PlanState *node)
  * This is used during planning and so must accept a Path, not a Plan.
  * We keep it here to be adjacent to the routines above, which also must
  * know which plan types support mark/restore.
- *
- * XXX Ideally, all plan node types would support mark/restore, and this
- * wouldn't be needed.  For now, this had better match the routines above.
- *
- * (However, since the only present use of mark/restore is in mergejoin,
- * there is no need to support mark/restore in any plan type that is not
- * capable of generating ordered output.  So the seqscan, tidscan,
- * and valuesscan support is actually useless code at present.)
  */
 bool
 ExecSupportsMarkRestore(Path *pathnode)
@@ -405,11 +381,8 @@ ExecSupportsMarkRestore(Path *pathnode)
 	 */
 	switch (pathnode->pathtype)
 	{
-		case T_SeqScan:
 		case T_IndexScan:
 		case T_IndexOnlyScan:
-		case T_TidScan:
-		case T_ValuesScan:
 		case T_Material:
 		case T_Sort:
 			return true;
@@ -426,7 +399,11 @@ ExecSupportsMarkRestore(Path *pathnode)
 			 * Although Result supports mark/restore if it has a child plan
 			 * that does, we presently come here only for ResultPath nodes,
 			 * which represent Result plans without a child plan.  So there is
-			 * nothing to recurse to and we can just say "false".
+			 * nothing to recurse to and we can just say "false".  (This means
+			 * that Result's support for mark/restore is in fact dead code.
+			 * We keep it since it's not much code, and someday the planner
+			 * might be smart enough to use it.  That would require making
+			 * this function smarter too, of course.)
 			 */
 			Assert(IsA(pathnode, ResultPath));
 			return false;
diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c
index ab13e4729ee..53cfda5f9c2 100644
--- a/src/backend/executor/nodeSeqscan.c
+++ b/src/backend/executor/nodeSeqscan.c
@@ -19,8 +19,6 @@
  *		ExecInitSeqScan			creates and initializes a seqscan node.
  *		ExecEndSeqScan			releases any storage allocated.
  *		ExecReScanSeqScan		rescans the relation
- *		ExecSeqMarkPos			marks scan position
- *		ExecSeqRestrPos			restores scan position
  */
 #include "postgres.h"
 
@@ -274,39 +272,3 @@ ExecReScanSeqScan(SeqScanState *node)
 
 	ExecScanReScan((ScanState *) node);
 }
-
-/* ----------------------------------------------------------------
- *		ExecSeqMarkPos(node)
- *
- *		Marks scan position.
- * ----------------------------------------------------------------
- */
-void
-ExecSeqMarkPos(SeqScanState *node)
-{
-	HeapScanDesc scan = node->ss_currentScanDesc;
-
-	heap_markpos(scan);
-}
-
-/* ----------------------------------------------------------------
- *		ExecSeqRestrPos
- *
- *		Restores scan position.
- * ----------------------------------------------------------------
- */
-void
-ExecSeqRestrPos(SeqScanState *node)
-{
-	HeapScanDesc scan = node->ss_currentScanDesc;
-
-	/*
-	 * Clear any reference to the previously returned tuple.  This is needed
-	 * because the slot is simply pointing at scan->rs_cbuf, which
-	 * heap_restrpos will change; we'd have an internally inconsistent slot if
-	 * we didn't do this.
-	 */
-	ExecClearTuple(node->ss_ScanTupleSlot);
-
-	heap_restrpos(scan);
-}
diff --git a/src/backend/executor/nodeTidscan.c b/src/backend/executor/nodeTidscan.c
index 3560f8440ab..1b2454d49de 100644
--- a/src/backend/executor/nodeTidscan.c
+++ b/src/backend/executor/nodeTidscan.c
@@ -19,8 +19,6 @@
  *		ExecInitTidScan		creates and initializes state info.
  *		ExecReScanTidScan	rescans the tid relation.
  *		ExecEndTidScan		releases all storage.
- *		ExecTidMarkPos		marks scan position.
- *		ExecTidRestrPos		restores scan position.
  */
 #include "postgres.h"
 
@@ -441,34 +439,6 @@ ExecEndTidScan(TidScanState *node)
 }
 
 /* ----------------------------------------------------------------
- *		ExecTidMarkPos
- *
- *		Marks scan position by marking the current tid.
- *		Returns nothing.
- * ----------------------------------------------------------------
- */
-void
-ExecTidMarkPos(TidScanState *node)
-{
-	node->tss_MarkTidPtr = node->tss_TidPtr;
-}
-
-/* ----------------------------------------------------------------
- *		ExecTidRestrPos
- *
- *		Restores scan position by restoring the current tid.
- *		Returns nothing.
- *
- *		XXX Assumes previously marked scan position belongs to current tid
- * ----------------------------------------------------------------
- */
-void
-ExecTidRestrPos(TidScanState *node)
-{
-	node->tss_TidPtr = node->tss_MarkTidPtr;
-}
-
-/* ----------------------------------------------------------------
  *		ExecInitTidScan
  *
  *		Initializes the tid scan's state information, creates
diff --git a/src/backend/executor/nodeValuesscan.c b/src/backend/executor/nodeValuesscan.c
index d49a4733865..8365b8c99f5 100644
--- a/src/backend/executor/nodeValuesscan.c
+++ b/src/backend/executor/nodeValuesscan.c
@@ -246,7 +246,6 @@ ExecInitValuesScan(ValuesScan *node, EState *estate, int eflags)
 	/*
 	 * Other node-specific setup
 	 */
-	scanstate->marked_idx = -1;
 	scanstate->curr_idx = -1;
 	scanstate->array_len = list_length(node->values_lists);
 
@@ -294,30 +293,6 @@ ExecEndValuesScan(ValuesScanState *node)
 }
 
 /* ----------------------------------------------------------------
- *		ExecValuesMarkPos
- *
- *		Marks scan position.
- * ----------------------------------------------------------------
- */
-void
-ExecValuesMarkPos(ValuesScanState *node)
-{
-	node->marked_idx = node->curr_idx;
-}
-
-/* ----------------------------------------------------------------
- *		ExecValuesRestrPos
- *
- *		Restores scan position.
- * ----------------------------------------------------------------
- */
-void
-ExecValuesRestrPos(ValuesScanState *node)
-{
-	node->curr_idx = node->marked_idx;
-}
-
-/* ----------------------------------------------------------------
  *		ExecReScanValuesScan
  *
  *		Rescans the relation.