diff --git a/cmd/go-tpc/tpch.go b/cmd/go-tpc/tpch.go
index 8905a1c..fb2c6a4 100644
--- a/cmd/go-tpc/tpch.go
+++ b/cmd/go-tpc/tpch.go
@@ -14,8 +14,8 @@ import (
 
 var tpchConfig tpch.Config
 
-queryTuningVars := []struct {
-	name string
+var queryTuningVars = []struct {
+	name  string
 	value string
 }{
 	// For optimal join order, esp. for q9.
@@ -26,12 +26,22 @@ queryTuningVars := []struct {
 	{"tidb_prefer_broadcast_join_by_exchange_data_size", "ON"},
 }
 
-func 
+func appendQueryTuningVarsToConnParams() {
+	for _, v := range queryTuningVars {
+		if !strings.Contains(connParams, v.name) {
+			connParams = fmt.Sprintf("%s&%s=%s", connParams, v.name, v.value)
+		}
+	}
+}
 
 func executeTpch(action string) {
-	if tpchConfig.EnableQueryTuning {
+	if action == "run" && driver == "mysql" && tpchConfig.EnableQueryTuning {
+		appendQueryTuningVarsToConnParams()
 	}
 
+	fmt.Println("Conn params: ")
+	fmt.Println(connParams)
+
 	openDB()
 	defer closeDB()
 
@@ -151,10 +161,6 @@ func registerTpch(root *cobra.Command) {
 		"enable-query-tuning",
 		true,
 		"Tune queries by setting some session variables known effective for tpch")
-	// cmdRun.PersistentFlags().StringVar(&tpchConfig.QueryTuningConfig.VarsRaw,
-	// 	"query-tuning-vars",
-	// 	"tidb_default_string_match_selectivity=0.1;tidb_opt_join_reorder_threshold=60;tidb_prefer_broadcast_join_by_exchange_data_size=ON",
-	// 	"Specify a sequence of session variables to set before executing each query, in the form of 'name=value', separated by semicolon. Defaulted to some variables known effective for tpch queries.")
 
 	var cmdCleanup = &cobra.Command{
 		Use:   "cleanup",
diff --git a/tpch/workload.go b/tpch/workload.go
index 48d28b9..6dd0926 100644
--- a/tpch/workload.go
+++ b/tpch/workload.go
@@ -199,18 +199,6 @@ func (w *Workloader) CheckPrepare(ctx context.Context, threadID int) error {
 	return nil
 }
 
-func (w *Workloader) setQueryTuningVars(ctx context.Context) error {
-	if w.cfg.QueryTuningConfig.Enable && w.cfg.Driver == "mysql" {
-		conn := w.getState(ctx).Conn
-		for _, v := range w.cfg.QueryTuningConfig.Vars {
-			if _, err := conn.ExecContext(ctx, fmt.Sprintf("SET @@session.%s", v)); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
-
 // Run runs workload
 func (w *Workloader) Run(ctx context.Context, threadID int) error {
 	s := w.getState(ctx)
@@ -221,10 +209,6 @@ func (w *Workloader) Run(ctx context.Context, threadID int) error {
 		}
 	}
 
-	if err := w.setQueryTuningVars(ctx); err != nil {
-		return fmt.Errorf("set query tuning variables failed %v", err)
-	}
-
 	queryName := w.cfg.QueryNames[s.queryIdx%len(w.cfg.QueryNames)]
 	query := query(w.cfg.Driver, queryName)
 	// only for driver == mysql and EnablePlanReplayer == true