diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 3550ef13ba..289dcc8ec0 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -216,7 +216,8 @@ InitializeParallelDSM(ParallelContext *pcxt)
 	int			i;
 	FixedParallelState *fps;
 	dsm_handle	session_dsm_handle = DSM_HANDLE_INVALID;
-	Snapshot	transaction_snapshot = GetTransactionSnapshot();
+	Snapshot	transaction_snapshot = IsolationUsesXactSnapshot() ?
+											GetTransactionSnapshot() : NULL;
 	Snapshot	active_snapshot = GetActiveSnapshot();
 
 	/* We might be running in a very short-lived memory context. */
@@ -254,8 +255,11 @@ InitializeParallelDSM(ParallelContext *pcxt)
 		shm_toc_estimate_chunk(&pcxt->estimator, guc_len);
 		combocidlen = EstimateComboCIDStateSpace();
 		shm_toc_estimate_chunk(&pcxt->estimator, combocidlen);
-		tsnaplen = EstimateSnapshotSpace(transaction_snapshot);
-		shm_toc_estimate_chunk(&pcxt->estimator, tsnaplen);
+		if (transaction_snapshot)
+		{
+			tsnaplen = EstimateSnapshotSpace(transaction_snapshot);
+			shm_toc_estimate_chunk(&pcxt->estimator, tsnaplen);
+		}
 		asnaplen = EstimateSnapshotSpace(active_snapshot);
 		shm_toc_estimate_chunk(&pcxt->estimator, asnaplen);
 		tstatelen = EstimateTransactionStateSpace();
@@ -366,11 +370,14 @@ InitializeParallelDSM(ParallelContext *pcxt)
 		SerializeComboCIDState(combocidlen, combocidspace);
 		shm_toc_insert(pcxt->toc, PARALLEL_KEY_COMBO_CID, combocidspace);
 
-		/* Serialize transaction snapshot and active snapshot. */
-		tsnapspace = shm_toc_allocate(pcxt->toc, tsnaplen);
-		SerializeSnapshot(transaction_snapshot, tsnapspace);
-		shm_toc_insert(pcxt->toc, PARALLEL_KEY_TRANSACTION_SNAPSHOT,
-					   tsnapspace);
+		/* Serialize transaction snapshot (if needed) and active snapshot. */
+		if (transaction_snapshot)
+		{
+			tsnapspace = shm_toc_allocate(pcxt->toc, tsnaplen);
+			SerializeSnapshot(transaction_snapshot, tsnapspace);
+			shm_toc_insert(pcxt->toc, PARALLEL_KEY_TRANSACTION_SNAPSHOT,
+						   tsnapspace);
+		}
 		asnapspace = shm_toc_allocate(pcxt->toc, asnaplen);
 		SerializeSnapshot(active_snapshot, asnapspace);
 		shm_toc_insert(pcxt->toc, PARALLEL_KEY_ACTIVE_SNAPSHOT, asnapspace);
@@ -1409,9 +1416,10 @@ ParallelWorkerMain(Datum main_arg)
 	AttachSession(*(dsm_handle *) session_dsm_handle_space);
 
 	/* Restore transaction snapshot. */
-	tsnapspace = shm_toc_lookup(toc, PARALLEL_KEY_TRANSACTION_SNAPSHOT, false);
-	RestoreTransactionSnapshot(RestoreSnapshot(tsnapspace),
-							   fps->parallel_leader_pgproc);
+	tsnapspace = shm_toc_lookup(toc, PARALLEL_KEY_TRANSACTION_SNAPSHOT, true);
+	if (tsnapspace)
+		RestoreTransactionSnapshot(RestoreSnapshot(tsnapspace),
+								   fps->parallel_leader_pgproc);
 
 	/* Restore active snapshot. */
 	asnapspace = shm_toc_lookup(toc, PARALLEL_KEY_ACTIVE_SNAPSHOT, false);