vtgate: Handle SET for sql_auto_is_null

go/vt/vtexplain/vtexplain_vttablet.go

@@ -286,6 +286,15 @@ func initTabletEnvironment(ddls []*sqlparser.DDL, opts *Options) error {
 				{sqltypes.NewVarBinary("1")},
 			},
 		},
+		"select @@sql_auto_is_null": {
+			Fields: []*querypb.Field{{
+				Type: sqltypes.Uint64,
+			}},
+			RowsAffected: 1,
+			Rows: [][]sqltypes.Value{
+				{sqltypes.NewVarBinary("0")},
+			},
+		},
 		"show variables like 'binlog_format'": {
 			Fields: []*querypb.Field{{
 				Type: sqltypes.VarChar,

go/vt/vtgate/executor.go

@@ -471,6 +471,19 @@ func (e *Executor) handleSet(ctx context.Context, safeSession *SafeSession, sql
 				safeSession.Options = &querypb.ExecuteOptions{}
 			}
 			safeSession.Options.SqlSelectLimit = val
+		case "sql_auto_is_null":
+			val, ok := v.(int64)
+			if !ok {
+				return nil, vterrors.Errorf(vtrpcpb.Code_INVALID_ARGUMENT, "unexpected value type for sql_auto_is_null: %T", v)
+			}
+			switch val {
+			case 0:
+				// This is the default setting for MySQL. Do nothing.
+			case 1:
+				return nil, vterrors.Errorf(vtrpcpb.Code_INVALID_ARGUMENT, "sql_auto_is_null is not currently supported")
+			default:
+				return nil, vterrors.Errorf(vtrpcpb.Code_INVALID_ARGUMENT, "unexpected value for sql_auto_is_null: %d", val)
+			}
 		case "character_set_results":
 			// This is a statement that mysql-connector-j sends at the beginning. We return a canned response for it.
 			switch v {

go/vt/vtgate/executor_test.go

@@ -329,6 +329,12 @@ func TestExecutorSet(t *testing.T) {
 	}, {
 		in:  "set skip_query_plan_cache = 0",
 		out: &vtgatepb.Session{Autocommit: true, Options: &querypb.ExecuteOptions{}},
+	}, {
+		in:  "set sql_auto_is_null = 0",
+		out: &vtgatepb.Session{Autocommit: true}, // no effect
+	}, {
+		in:  "set sql_auto_is_null = 1",
+		err: "sql_auto_is_null is not currently supported",
 	}}
 	for _, tcase := range testcases {
 		session := NewSafeSession(&vtgatepb.Session{Autocommit: true})

go/vt/vttablet/tabletserver/connpool/dbconn.go

@@ -216,6 +216,7 @@ func (dbc *DBConn) streamOnce(ctx context.Context, query string, callback func(*
 var (
 	getModeSQL    = "select @@global.sql_mode"
 	getAutocommit = "select @@autocommit"
+	getAutoIsNull = "select @@sql_auto_is_null"
 	showBinlog    = "show variables like 'binlog_format'"
 )
 
@@ -245,6 +246,16 @@ func (dbc *DBConn) VerifyMode(strictTransTables bool) (BinlogFormat, error) {
 	if !strings.Contains(qr.Rows[0][0].ToString(), "1") {
 		return 0, fmt.Errorf("require autocommit to be 1: got %s", qr.Rows[0][0].ToString())
 	}
+	qr, err = dbc.conn.ExecuteFetch(getAutoIsNull, 2, false)
+	if err != nil {
+		return 0, fmt.Errorf("could not verify mode: %v", err)
+	}
+	if len(qr.Rows) != 1 {
+		return 0, fmt.Errorf("incorrect rowcount received for %s: %d", getAutoIsNull, len(qr.Rows))
+	}
+	if !strings.Contains(qr.Rows[0][0].ToString(), "0") {
+		return 0, fmt.Errorf("require sql_auto_is_null to be 0: got %s", qr.Rows[0][0].ToString())
+	}
 	qr, err = dbc.conn.ExecuteFetch(showBinlog, 10, false)
 	if err != nil {
 		return 0, fmt.Errorf("could not fetch binlog format: %v", err)

go/vt/vttablet/tabletserver/query_executor_test.go

@@ -2107,6 +2107,15 @@ func getQueryExecutorSupportedQueries(testTableHasMultipleUniqueKeys bool) map[s
 				{sqltypes.NewVarBinary("1")},
 			},
 		},
+		"select @@sql_auto_is_null": {
+			Fields: []*querypb.Field{{
+				Type: sqltypes.Uint64,
+			}},
+			RowsAffected: 1,
+			Rows: [][]sqltypes.Value{
+				{sqltypes.NewVarBinary("0")},
+			},
+		},
 		"show variables like 'binlog_format'": {
 			Fields: []*querypb.Field{{
 				Type: sqltypes.VarChar,

go/vt/vttablet/tabletserver/schema/schematest/schematest.go

@@ -57,6 +57,15 @@ func Queries() map[string]*sqltypes.Result {
 				{sqltypes.NewVarBinary("1")},
 			},
 		},
+		"select @@sql_auto_is_null": {
+			Fields: []*querypb.Field{{
+				Type: sqltypes.Uint64,
+			}},
+			RowsAffected: 1,
+			Rows: [][]sqltypes.Value{
+				{sqltypes.NewVarBinary("0")},
+			},
+		},
 		"show variables like 'binlog_format'": {
 			Fields: []*querypb.Field{{
 				Type: sqltypes.VarChar,

go/vt/vttablet/tabletserver/tabletserver_test.go

@@ -2897,6 +2897,15 @@ func getSupportedQueries() map[string]*sqltypes.Result {
 				{sqltypes.NewVarBinary("1")},
 			},
 		},
+		"select @@sql_auto_is_null": {
+			Fields: []*querypb.Field{{
+				Type: sqltypes.Uint64,
+			}},
+			RowsAffected: 1,
+			Rows: [][]sqltypes.Value{
+				{sqltypes.NewVarBinary("0")},
+			},
+		},
 		"show variables like 'binlog_format'": {
 			Fields: []*querypb.Field{{
 				Type: sqltypes.VarChar,