diff --git a/common/config.go b/common/config.go
index 15818b8a..d5036409 100644
--- a/common/config.go
+++ b/common/config.go
@@ -14,7 +14,7 @@ var LogTimeout time.Duration
 const EnableDebug bool = false //true
 
 // use virtual storage or not
-const EnableOnMemStorage = true
+const EnableOnMemStorage = false //true
 
 // when this is true, virtual storage use is suppressed
 // for test case which can't work with virtual storage
diff --git a/samehada/samehada.go b/samehada/samehada.go
index 37d159fc..e77195ab 100644
--- a/samehada/samehada.go
+++ b/samehada/samehada.go
@@ -146,12 +146,12 @@ func NewSamehadaDB(dbName string, memKBytes int) *SamehadaDB {
 
 	//chkpntMgr := concurrency.NewCheckpointManager(shi.GetTransactionManager(), shi.GetLogManager(), shi.GetBufferPoolManager())
 	//chkpntMgr.StartCheckpointTh()
-	shi.GetCheckpointManager().StartCheckpointTh()
+	//shi.GetCheckpointManager().StartCheckpointTh()
 
 	// statics data is updated periodically by this thread with full scan of all tables
 	// this may be not good implementation of statistics, but it is enough for now...
 	statUpdater := concurrency.NewStatisticsUpdater(shi.GetTransactionManager(), c)
-	statUpdater.StartStaticsUpdaterTh()
+	//statUpdater.StartStaticsUpdaterTh()
 
 	return &SamehadaDB{shi, c, exec_engine, statUpdater}
 }
diff --git a/samehada/samehada_test/samehada_test.go b/samehada/samehada_test/samehada_test.go
index 7eda5214..46d0631e 100644
--- a/samehada/samehada_test/samehada_test.go
+++ b/samehada/samehada_test/samehada_test.go
@@ -336,8 +336,8 @@ func TestParallelQueryIssue(t *testing.T) {
 		os.Remove(t.Name() + ".log")
 	}
 
-	db := samehada.NewSamehadaDB(t.Name(), 5000) // 5MB
-	opTimes := 100000
+	db := samehada.NewSamehadaDB(t.Name(), 5000*1000) //5GB // 5MB
+	opTimes := 100000                                 //500000                                 //1000000
 
 	queryVals := make([]int32, 0)
 
@@ -350,9 +350,16 @@ func TestParallelQueryIssue(t *testing.T) {
 	err, _ := db.ExecuteSQL("CREATE TABLE k_v_list(k INT, v INT);")
 	testingpkg.Assert(t, err == nil, "failed to create table")
 
+	insCh := make(chan int32)
 	for ii := 0; ii < opTimes; ii++ {
-		err, _ = db.ExecuteSQLRetValues(fmt.Sprintf("INSERT INTO k_v_list(k, v) VALUES (%d, %d);", queryVals[ii], queryVals[ii]))
-		testingpkg.Assert(t, err == nil, "failed to insert val: "+strconv.Itoa(int(queryVals[ii])))
+		go func(val int32) {
+			err, _ = db.ExecuteSQLRetValues(fmt.Sprintf("INSERT INTO k_v_list(k, v) VALUES (%d, %d);", val, val))
+			insCh <- val
+		}(queryVals[ii])
+		//testingpkg.Assert(t, err == nil, "failed to insert val: "+strconv.Itoa(int(queryVals[ii])))
+	}
+	for ii := 0; ii < opTimes; ii++ {
+		<-insCh
 	}
 
 	// shuffle query vals array elements