expression: pushdown reverse to TiFlash

expression/expr_to_pb_test.go

@@ -1136,6 +1136,16 @@ func TestExprPushDownToFlash(t *testing.T) {
 	require.NoError(t, err)
 	exprs = append(exprs, function)
 
+	// ReverseUTF8
+	function, err = NewFunction(mock.NewContext(), ast.Reverse, types.NewFieldType(mysql.TypeString), stringColumn)
+	require.NoError(t, err)
+	exprs = append(exprs, function)
+
+	// Reverse
+	function, err = NewFunction(mock.NewContext(), ast.Reverse, types.NewFieldType(mysql.TypeBlob), stringColumn)
+	require.NoError(t, err)
+	exprs = append(exprs, function)
+
 	pushed, remained = PushDownExprs(sc, exprs, client, kv.TiFlash)
 	require.Len(t, pushed, len(exprs))
 	require.Len(t, remained, 0)

expression/expression.go

@@ -1070,15 +1070,17 @@ func scalarExprSupportedByFlash(function *ScalarFunction) bool {
 			return false
 		}
 		return true
-	case ast.Substr, ast.Substring, ast.Left, ast.Right, ast.CharLength, ast.SubstringIndex:
+	case ast.Substr, ast.Substring, ast.Left, ast.Right, ast.CharLength, ast.SubstringIndex, ast.Reverse:
 		switch function.Function.PbCode() {
 		case
 			tipb.ScalarFuncSig_LeftUTF8,
 			tipb.ScalarFuncSig_RightUTF8,
 			tipb.ScalarFuncSig_CharLengthUTF8,
 			tipb.ScalarFuncSig_Substring2ArgsUTF8,
 			tipb.ScalarFuncSig_Substring3ArgsUTF8,
-			tipb.ScalarFuncSig_SubstringIndex:
+			tipb.ScalarFuncSig_SubstringIndex,
+			tipb.ScalarFuncSig_ReverseUTF8,
+			tipb.ScalarFuncSig_Reverse:
 			return true
 		}
 	case ast.Cast:

planner/core/integration_test.go

@@ -3212,6 +3212,76 @@ func TestDistinctScalarFunctionPushDown(t *testing.T) {
 	))
 }
 
+func TestReverseUTF8PushDownToTiFlash(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (a varchar(256))")
+	tk.MustExec("insert into t values('pingcap')")
+	tk.MustExec("set @@tidb_allow_mpp=1; set @@tidb_enforce_mpp=1;")
+	tk.MustExec("set @@tidb_isolation_read_engines = 'tiflash'")
+
+	// Create virtual tiflash replica info.
+	dom := domain.GetDomain(tk.Session())
+	is := dom.InfoSchema()
+	db, exists := is.SchemaByName(model.NewCIStr("test"))
+	require.True(t, exists)
+	for _, tblInfo := range db.Tables {
+		if tblInfo.Name.L == "t" {
+			tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
+				Count:     1,
+				Available: true,
+			}
+		}
+	}
+
+	rows := [][]interface{}{
+		{"TableReader_9", "root", "data:ExchangeSender_8"},
+		{"└─ExchangeSender_8", "mpp[tiflash]", "ExchangeType: PassThrough"},
+		{"  └─Projection_4", "mpp[tiflash]", "reverse(test.t.a)->Column#3"},
+		{"    └─TableFullScan_7", "mpp[tiflash]", "keep order:false, stats:pseudo"},
+	}
+
+	tk.MustQuery("explain select reverse(a) from t;").CheckAt([]int{0, 2, 4}, rows)
+}
+
+func TestReversePushDownToTiFlash(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (a binary(32))")
+	tk.MustExec("insert into t values('pingcap')")
+	tk.MustExec("set @@tidb_allow_mpp=1; set @@tidb_enforce_mpp=1;")
+	tk.MustExec("set @@tidb_isolation_read_engines = 'tiflash'")
+
+	// Create virtual tiflash replica info.
+	dom := domain.GetDomain(tk.Session())
+	is := dom.InfoSchema()
+	db, exists := is.SchemaByName(model.NewCIStr("test"))
+	require.True(t, exists)
+	for _, tblInfo := range db.Tables {
+		if tblInfo.Name.L == "t" {
+			tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
+				Count:     1,
+				Available: true,
+			}
+		}
+	}
+
+	rows := [][]interface{}{
+		{"TableReader_9", "root", "data:ExchangeSender_8"},
+		{"└─ExchangeSender_8", "mpp[tiflash]", "ExchangeType: PassThrough"},
+		{"  └─Projection_4", "mpp[tiflash]", "reverse(test.t.a)->Column#3"},
+		{"    └─TableFullScan_7", "mpp[tiflash]", "keep order:false, stats:pseudo"},
+	}
+
+	tk.MustQuery("explain select reverse(a) from t;").CheckAt([]int{0, 2, 4}, rows)
+}
+
 func TestExplainAnalyzePointGet(t *testing.T) {
 	store, clean := testkit.CreateMockStore(t)
 	defer clean()