enable select for update in autocommit mode

go/vt/vttablet/tabletserver/query_executor.go

@@ -149,7 +149,10 @@ func (qre *QueryExecutor) Execute() (reply *sqltypes.Result, err error) {
 		case planbuilder.PlanPassSelect:
 			return qre.execSelect()
 		case planbuilder.PlanSelectLock:
-			return nil, vterrors.Errorf(vtrpcpb.Code_FAILED_PRECONDITION, "disallowed outside transaction")
+			if false || !qre.tsv.qe.autoCommit.Get() {
+				return nil, vterrors.Errorf(vtrpcpb.Code_FAILED_PRECONDITION, "disallowed outside transaction")
+			}
+			return qre.execDmlAutoCommit()
 		case planbuilder.PlanSet:
 			return qre.execSet()
 		case planbuilder.PlanOtherRead:
@@ -244,6 +247,8 @@ func (qre *QueryExecutor) execDmlAutoCommit() (reply *sqltypes.Result, err error
 			reply, err = qre.execDMLSubquery(conn)
 		case planbuilder.PlanUpsertPK:
 			reply, err = qre.execUpsertPK(conn)
+		case planbuilder.PlanSelectLock:
+			return qre.execDirect(conn)
 		default:
 			return nil, vterrors.Errorf(vtrpcpb.Code_INVALID_ARGUMENT, "unsupported query: %s", qre.query)
 		}

go/vt/vttablet/tabletserver/query_executor_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package tabletserver
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"math/rand"
@@ -846,7 +847,7 @@ func TestQueryExecutorPlanDmlMessage(t *testing.T) {
 	conn.Recycle()
 }
 
-func TestQueryExecutorPlanDmlAutoCommit(t *testing.T) {
+func TestQueryExecutorPlanUpdateAutoCommit(t *testing.T) {
 	db := setUpQueryExecutorTest(t)
 	defer db.Close()
 	query := "update test_table set name = 2 where pk in (1) /* _stream test_table (pk ) (1 ); */"
@@ -866,6 +867,26 @@ func TestQueryExecutorPlanDmlAutoCommit(t *testing.T) {
 	}
 }
 
+func TestQueryExecutorPlanDeleteAutoCommit(t *testing.T) {
+	db := setUpQueryExecutorTest(t)
+	defer db.Close()
+	query := "delete from test_table where pk in (1) /* _stream test_table (pk ) (1 ); */"
+	want := &sqltypes.Result{}
+	db.AddQuery(query, want)
+	ctx := context.Background()
+	tsv := newTestTabletServer(ctx, noFlags, db)
+	qre := newTestQueryExecutor(ctx, tsv, query, 0)
+	defer tsv.StopService()
+	checkPlanID(t, planbuilder.PlanDMLPK, qre.plan.PlanID)
+	got, err := qre.Execute()
+	if err != nil {
+		t.Fatalf("qre.Execute() = %v, want nil", err)
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("got: %v, want: %v", got, want)
+	}
+}
+
 func TestQueryExecutorPlanDmlAutoCommitTransactionIsolation(t *testing.T) {
 	db := setUpQueryExecutorTest(t)
 	defer db.Close()
@@ -1072,7 +1093,7 @@ func TestQueryExecutorPlanPassSelectWithLockOutsideATransaction(t *testing.T) {
 		Fields: getTestTableFields(),
 	})
 	ctx := context.Background()
-	tsv := newTestTabletServer(ctx, noFlags, db)
+	tsv := newTestTabletServer(ctx, noAutoCommit, db)
 	qre := newTestQueryExecutor(ctx, tsv, query, 0)
 	defer tsv.StopService()
 	checkPlanID(t, planbuilder.PlanSelectLock, qre.plan.PlanID)
@@ -1082,6 +1103,42 @@ func TestQueryExecutorPlanPassSelectWithLockOutsideATransaction(t *testing.T) {
 	}
 }
 
+// When handling DMLs with an owned secondary vindex, vtgate will sometimes send
+// a SELECT ... FOR UPDATE query to find out the current value of the secondary
+// index field, so this needs to be supported when autocommit is enabled.
+func TestQueryExecutorPlanSelectForUpdateAutoCommit(t *testing.T) {
+	db := setUpQueryExecutorTest(t)
+	defer db.Close()
+	query := "select name from test_table where pk in (1) limit 10001 for update"
+	want := &sqltypes.Result{
+		Fields: []*querypb.Field{
+			{
+				Name: "name",
+				Type: sqltypes.VarChar,
+			},
+		},
+		RowsAffected: 1,
+		Rows: [][]sqltypes.Value{
+			{sqltypes.NewVarChar("name")},
+		},
+	}
+	db.AddQuery(query, want)
+	ctx := context.Background()
+	tsv := newTestTabletServer(ctx, noFlags, db)
+	qre := newTestQueryExecutor(ctx, tsv, query, 0)
+	defer tsv.StopService()
+	checkPlanID(t, planbuilder.PlanSelectLock, qre.plan.PlanID)
+	got, err := qre.Execute()
+	if err != nil {
+		t.Fatalf("qre.Execute() = %v, want nil", err)
+	}
+	if !reflect.DeepEqual(got, want) {
+		x, _ := json.MarshalIndent(got, "", "    ")
+		y, _ := json.MarshalIndent(want, "", "    ")
+		t.Fatalf("got: %v, want: %v", string(x), string(y))
+	}
+}
+
 func TestQueryExecutorPlanPassSelect(t *testing.T) {
 	db := setUpQueryExecutorTest(t)
 	defer db.Close()
@@ -1813,6 +1870,7 @@ const (
 	smallTxPool
 	noTwopc
 	shortTwopcAge
+	noAutoCommit
 )
 
 // newTestQueryExecutor uses a package level variable testTabletServer defined in tabletserver_test.go
@@ -1826,7 +1884,11 @@ func newTestTabletServer(ctx context.Context, flags executorFlags, db *fakesqldb
 	} else {
 		config.TransactionCap = 100
 	}
-	config.EnableAutoCommit = true
+	if flags&noAutoCommit > 0 {
+		config.EnableAutoCommit = false
+	} else {
+		config.EnableAutoCommit = true
+	}
 	if flags&enableStrictTableACL > 0 {
 		config.StrictTableACL = true
 	} else {
@@ -2001,6 +2063,12 @@ func getQueryExecutorSupportedQueries(testTableHasMultipleUniqueKeys bool) map[s
 				Type: sqltypes.Int32,
 			}},
 		},
+		"select name from test_table where 1 != 1": {
+			Fields: []*querypb.Field{{
+				Name: "name",
+				Type: sqltypes.VarChar,
+			}},
+		},
 		"describe test_table": {
 			Fields:       mysql.DescribeTableFields,
 			RowsAffected: 3,