3 files changed, 94 insertions, 0 deletions

diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c
index 9b7f470ee28..f61b3abf326 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -421,11 +421,39 @@ ExecEndIndexOnlyScan(IndexOnlyScanState *node)
 
 /* ----------------------------------------------------------------
  *		ExecIndexOnlyMarkPos
+ *
+ * Note: we assume that no caller attempts to set a mark before having read
+ * at least one tuple.  Otherwise, ioss_ScanDesc might still be NULL.
  * ----------------------------------------------------------------
  */
 void
 ExecIndexOnlyMarkPos(IndexOnlyScanState *node)
 {
+	EState	   *estate = node->ss.ps.state;
+
+	if (estate->es_epqTuple != NULL)
+	{
+		/*
+		 * We are inside an EvalPlanQual recheck.  If a test tuple exists for
+		 * this relation, then we shouldn't access the index at all.  We would
+		 * instead need to save, and later restore, the state of the
+		 * es_epqScanDone flag, so that re-fetching the test tuple is
+		 * possible.  However, given the assumption that no caller sets a mark
+		 * at the start of the scan, we can only get here with es_epqScanDone
+		 * already set, and so no state need be saved.
+		 */
+		Index		scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
+
+		Assert(scanrelid > 0);
+		if (estate->es_epqTupleSet[scanrelid - 1])
+		{
+			/* Verify the claim above */
+			if (!estate->es_epqScanDone[scanrelid - 1])
+				elog(ERROR, "unexpected ExecIndexOnlyMarkPos call in EPQ recheck");
+			return;
+		}
+	}
+
 	index_markpos(node->ioss_ScanDesc);
 }
 
@@ -436,6 +464,23 @@ ExecIndexOnlyMarkPos(IndexOnlyScanState *node)
 void
 ExecIndexOnlyRestrPos(IndexOnlyScanState *node)
 {
+	EState	   *estate = node->ss.ps.state;
+
+	if (estate->es_epqTuple != NULL)
+	{
+		/* See comments in ExecIndexOnlyMarkPos */
+		Index		scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
+
+		Assert(scanrelid > 0);
+		if (estate->es_epqTupleSet[scanrelid - 1])
+		{
+			/* Verify the claim above */
+			if (!estate->es_epqScanDone[scanrelid - 1])
+				elog(ERROR, "unexpected ExecIndexOnlyRestrPos call in EPQ recheck");
+			return;
+		}
+	}
+
 	index_restrpos(node->ioss_ScanDesc);
 }
 
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 54fafa5033f..eed69a0c665 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -849,11 +849,39 @@ ExecEndIndexScan(IndexScanState *node)
 
 /* ----------------------------------------------------------------
  *		ExecIndexMarkPos
+ *
+ * Note: we assume that no caller attempts to set a mark before having read
+ * at least one tuple.  Otherwise, iss_ScanDesc might still be NULL.
  * ----------------------------------------------------------------
  */
 void
 ExecIndexMarkPos(IndexScanState *node)
 {
+	EState	   *estate = node->ss.ps.state;
+
+	if (estate->es_epqTuple != NULL)
+	{
+		/*
+		 * We are inside an EvalPlanQual recheck.  If a test tuple exists for
+		 * this relation, then we shouldn't access the index at all.  We would
+		 * instead need to save, and later restore, the state of the
+		 * es_epqScanDone flag, so that re-fetching the test tuple is
+		 * possible.  However, given the assumption that no caller sets a mark
+		 * at the start of the scan, we can only get here with es_epqScanDone
+		 * already set, and so no state need be saved.
+		 */
+		Index		scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
+
+		Assert(scanrelid > 0);
+		if (estate->es_epqTupleSet[scanrelid - 1])
+		{
+			/* Verify the claim above */
+			if (!estate->es_epqScanDone[scanrelid - 1])
+				elog(ERROR, "unexpected ExecIndexMarkPos call in EPQ recheck");
+			return;
+		}
+	}
+
 	index_markpos(node->iss_ScanDesc);
 }
 
@@ -864,6 +892,23 @@ ExecIndexMarkPos(IndexScanState *node)
 void
 ExecIndexRestrPos(IndexScanState *node)
 {
+	EState	   *estate = node->ss.ps.state;
+
+	if (estate->es_epqTuple != NULL)
+	{
+		/* See comments in ExecIndexMarkPos */
+		Index		scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
+
+		Assert(scanrelid > 0);
+		if (estate->es_epqTupleSet[scanrelid - 1])
+		{
+			/* Verify the claim above */
+			if (!estate->es_epqScanDone[scanrelid - 1])
+				elog(ERROR, "unexpected ExecIndexRestrPos call in EPQ recheck");
+			return;
+		}
+	}
+
 	index_restrpos(node->iss_ScanDesc);
 }
 
diff --git a/src/backend/executor/nodeMergejoin.c b/src/backend/executor/nodeMergejoin.c
index b52946f180a..ec5f82f6a92 100644
--- a/src/backend/executor/nodeMergejoin.c
+++ b/src/backend/executor/nodeMergejoin.c
@@ -1502,6 +1502,10 @@ ExecInitMergeJoin(MergeJoin *node, EState *estate, int eflags)
 	 *
 	 * Currently, only Material wants the extra MARKs, and it will be helpful
 	 * only if eflags doesn't specify REWIND.
+	 *
+	 * Note that for IndexScan and IndexOnlyScan, it is *necessary* that we
+	 * not set mj_ExtraMarks; otherwise we might attempt to set a mark before
+	 * the first inner tuple, which they do not support.
 	 */
 	if (IsA(innerPlan(node), Material) &&
 		(eflags & EXEC_FLAG_REWIND) == 0 &&