diff --git a/expression/distsql_builtin.go b/expression/distsql_builtin.go
index 8d2c2ad4d7826..5f344cbad8478 100644
--- a/expression/distsql_builtin.go
+++ b/expression/distsql_builtin.go
@@ -668,10 +668,10 @@ func getSignatureByPB(ctx sessionctx.Context, sigCode tipb.ScalarFuncSig, tp *ti
 		f = &builtinUUIDSig{base}
 	case tipb.ScalarFuncSig_LikeSig:
 		f = &builtinLikeSig{base, nil, false, sync.Once{}}
-	// case tipb.ScalarFuncSig_RegexpSig:
-	// 	f = &builtinRegexpSig{base}
-	// case tipb.ScalarFuncSig_RegexpUTF8Sig:
-	// 	f = &builtinRegexpUTF8Sig{base}
+	case tipb.ScalarFuncSig_RegexpSig:
+		f = newBuiltinRegexpSig(base)
+	case tipb.ScalarFuncSig_RegexpUTF8Sig:
+		f = newBuiltinRegexpUTF8Sig(base)
 	case tipb.ScalarFuncSig_JsonExtractSig:
 		f = &builtinJSONExtractSig{base}
 	case tipb.ScalarFuncSig_JsonUnquoteSig:
diff --git a/expression/distsql_builtin_test.go b/expression/distsql_builtin_test.go
index 26f47169e9098..7cb7cc972b029 100644
--- a/expression/distsql_builtin_test.go
+++ b/expression/distsql_builtin_test.go
@@ -847,6 +847,28 @@ func TestPBToExprWithNewCollation(t *testing.T) {
 	}
 }
 
+// Test convert various scalar functions.
+func TestPBToScalarFuncExpr(t *testing.T) {
+	sc := new(stmtctx.StatementContext)
+	fieldTps := make([]*types.FieldType, 1)
+	exprs := []*tipb.Expr{
+		{
+			Tp:        tipb.ExprType_ScalarFunc,
+			Sig:       tipb.ScalarFuncSig_RegexpSig,
+			FieldType: ToPBFieldType(newStringFieldType()),
+		},
+		{
+			Tp:        tipb.ExprType_ScalarFunc,
+			Sig:       tipb.ScalarFuncSig_RegexpUTF8Sig,
+			FieldType: ToPBFieldType(newStringFieldType()),
+		},
+	}
+	for _, expr := range exprs {
+		_, err := PBToExpr(expr, fieldTps, sc)
+		require.NoError(t, err)
+	}
+}
+
 func datumExpr(t *testing.T, d types.Datum) *tipb.Expr {
 	expr := new(tipb.Expr)
 	switch d.Kind() {
diff --git a/infoschema/cluster_tables_test.go b/infoschema/cluster_tables_test.go
index da4432ddb2c8e..86d886886b3f1 100644
--- a/infoschema/cluster_tables_test.go
+++ b/infoschema/cluster_tables_test.go
@@ -245,6 +245,12 @@ func TestSelectClusterTable(t *testing.T) {
 	re := tk.MustQuery("select * from `CLUSTER_statements_summary`")
 	require.NotNil(t, re)
 	require.Greater(t, len(re.Rows()), 0)
+	re = tk.MustQuery("select * from `CLUSTER_statements_summary` where table_names REGEXP '\\binformation_schema\\.'")
+	require.NotNil(t, re)
+	require.Equal(t, len(re.Rows()), 0)
+	re = tk.MustQuery("select * from `CLUSTER_statements_summary` where table_names REGEXP 'information_schema\\.'")
+	require.NotNil(t, re)
+	require.Greater(t, len(re.Rows()), 0)
 	// Test for TiDB issue 14915.
 	re = tk.MustQuery("select sum(exec_count*avg_mem) from cluster_statements_summary_history group by schema_name,digest,digest_text;")
 	require.NotNil(t, re)