diff --git a/include/tableam/handler.h b/include/tableam/handler.h
index 4e8f3735c..359f964b7 100644
--- a/include/tableam/handler.h
+++ b/include/tableam/handler.h
@@ -209,7 +209,9 @@ typedef struct ParallelOScanDescData
 	dsm_handle	dsmHandle;
 	/* debug only */
 	int			cur_int_pageno;
-	bool		worker_active[10];
+#ifdef USE_ASSERT_CHECKING
+	bool		worker_active[1024];
+#endif
 } ParallelOScanDescData;
 
 typedef ParallelOScanDescData *ParallelOScanDesc;
diff --git a/src/btree/scan.c b/src/btree/scan.c
index 9eca8a697..5ec93d8b8 100644
--- a/src/btree/scan.c
+++ b/src/btree/scan.c
@@ -1039,13 +1039,18 @@ init_btree_seq_scan(BTreeSeqScan *scan)
 		 * after all workers completed their scans).
 		 */
 		SpinLockAcquire(&poscan->workerStart);
+#ifdef USE_ASSERT_CHECKING
 		for (scan->workerNumber = 0; poscan->worker_active[scan->workerNumber] == true; scan->workerNumber++)
 		{
 		}
 
 		poscan->worker_active[scan->workerNumber] = true;
 		poscan->nworkers = scan->workerNumber + 1;
-		/* leader */
+#else
+		scan->workerNumber = poscan->nworkers;
+		poscan->nworkers++;
+#endif
+		/* Scan leader */
 		if (scan->workerNumber == 0)
 		{
 			Assert(!(poscan->flags & O_PARALLEL_LEADER_STARTED));