Revert "sink/mysql: explicit_defaults_for_timestamp compatibility wit…

…h mysql (#1638) (#1659)"

This reverts commit 7a35809.

cdc/sink/mysql.go

@@ -69,8 +69,6 @@ const (
 // SyncpointTableName is the name of table where all syncpoint maps sit
 const syncpointTableName string = "syncpoint_v1"
 
-const tidbVersionString string = "TiDB"
-
 var validSchemes = map[string]bool{
 	"mysql":     true,
 	"mysql+ssl": true,
@@ -308,37 +306,21 @@ var defaultParams = &sinkParams{
 	safeMode:            defaultSafeMode,
 }
 
-func checkIsTiDB(ctx context.Context, db *sql.DB) (bool, error) {
-	var value string
-	querySQL := "select version();"
-	err := db.QueryRowContext(ctx, querySQL).Scan(&value)
-	if err != nil && err != sql.ErrNoRows {
-		return false, errors.Annotate(cerror.WrapError(cerror.ErrMySQLQueryError, err), "failed to select version")
-	}
-	return strings.Contains(value, tidbVersionString), nil
-}
-
-func checkTiDBVariable(ctx context.Context, db *sql.DB, variableName, defaultValue string) (
-	sinkURIParameter string,
-	err error,
-) {
+func checkTiDBVariable(ctx context.Context, db *sql.DB, variableName, defaultValue string) (string, error) {
 	var name string
 	var value string
 	querySQL := fmt.Sprintf("show session variables like '%s';", variableName)
-	err = db.QueryRowContext(ctx, querySQL).Scan(&name, &value)
+	err := db.QueryRowContext(ctx, querySQL).Scan(&name, &value)
 	if err != nil && err != sql.ErrNoRows {
 		errMsg := "fail to query session variable " + variableName
-		err = errors.Annotate(cerror.WrapError(cerror.ErrMySQLQueryError, err), errMsg)
-		return
+		return "", errors.Annotate(cerror.WrapError(cerror.ErrMySQLQueryError, err), errMsg)
 	}
+	// session variable works, use given default value
 	if err == nil {
-		// session variable exists, use given default value
-		sinkURIParameter = defaultValue
-	} else {
-		// session variable does not exist, sinkURIParameter is "" and will be ignored
-		err = nil
+		return defaultValue, nil
 	}
-	return
+	// session variable not exists, return "" to ignore it
+	return "", nil
 }
 
 func configureSinkURI(
@@ -377,21 +359,6 @@ func configureSinkURI(
 		dsnCfg.Params["tidb_txn_mode"] = txnMode
 	}
 
-	isTiDB, err := checkIsTiDB(ctx, testDB)
-	if err != nil {
-		return "", err
-	}
-	// variable `explicit_defaults_for_timestamp` is readonly in TiDB, we don't
-	// need to set it. Yet Default value in MySQL 5.7 is `OFF`
-	// ref: https://docs.pingcap.com/tidb/stable/mysql-compatibility#default-differences
-	if !isTiDB {
-		explicitTs, err := checkTiDBVariable(ctx, testDB, "explicit_defaults_for_timestamp", "ON")
-		if err != nil {
-			return "", err
-		}
-		dsnCfg.Params["explicit_defaults_for_timestamp"] = explicitTs
-	}
-
 	dsnClone := dsnCfg.Clone()
 	dsnClone.Passwd = "******"
 	log.Info("sink uri is configured", zap.String("format dsn", dsnClone.FormatDSN()))

cdc/sink/mysql_test.go

@@ -704,29 +704,6 @@ func (s MySQLSinkSuite) TestConfigureSinkURI(c *check.C) {
 		c.Assert(err, check.IsNil)
 		defer db.Close()
 
-		dsn, err := dmysql.ParseDSN("root:123456@tcp(127.0.0.1:4000)/")
-		c.Assert(err, check.IsNil)
-		params := defaultParams.Clone()
-		dsnStr, err := configureSinkURI(context.TODO(), dsn, params, db)
-		c.Assert(err, check.IsNil)
-		expectedParams := []string{
-			"tidb_txn_mode=optimistic",
-			"readTimeout=2m",
-			"writeTimeout=2m",
-			"allow_auto_random_explicit_insert=1",
-			"explicit_defaults_for_timestamp=ON",
-		}
-		for _, param := range expectedParams {
-			c.Assert(strings.Contains(dsnStr, param), check.IsTrue)
-		}
-		c.Assert(strings.Contains(dsnStr, "time_zone"), check.IsFalse)
-	}
-
-	testDefaultParamsTiDB := func() {
-		db, err := mockTestDBTiDB()
-		c.Assert(err, check.IsNil)
-		defer db.Close()
-
 		dsn, err := dmysql.ParseDSN("root:123456@tcp(127.0.0.1:4000)/")
 		c.Assert(err, check.IsNil)
 		params := defaultParams.Clone()
@@ -782,7 +759,6 @@ func (s MySQLSinkSuite) TestConfigureSinkURI(c *check.C) {
 	}
 
 	testDefaultParams()
-	testDefaultParamsTiDB()
 	testTimezoneParam()
 	testTimeoutParams()
 }
@@ -901,34 +877,6 @@ func mockTestDB() (*sql.DB, error) {
 	mock.ExpectQuery("show session variables like 'tidb_txn_mode';").WillReturnRows(
 		sqlmock.NewRows(columns).AddRow("tidb_txn_mode", "pessimistic"),
 	)
-	// Simulate the default value in MySQL5.7 is OFF
-	mock.ExpectQuery("select version\\(\\);").WillReturnRows(
-		sqlmock.NewRows([]string{"version"}).AddRow("5.7.32"),
-	)
-	// Simulate the default value in MySQL5.7 is OFF
-	mock.ExpectQuery("show session variables like 'explicit_defaults_for_timestamp';").WillReturnRows(
-		sqlmock.NewRows(columns).AddRow("explicit_defaults_for_timestamp", "OFF"),
-	)
-	mock.ExpectClose()
-	return db, nil
-}
-
-func mockTestDBTiDB() (*sql.DB, error) {
-	// mock for test db, which is used querying TiDB session variable
-	db, mock, err := sqlmock.New()
-	if err != nil {
-		return nil, err
-	}
-	columns := []string{"Variable_name", "Value"}
-	mock.ExpectQuery("show session variables like 'allow_auto_random_explicit_insert';").WillReturnRows(
-		sqlmock.NewRows(columns).AddRow("allow_auto_random_explicit_insert", "1"),
-	)
-	mock.ExpectQuery("show session variables like 'tidb_txn_mode';").WillReturnRows(
-		sqlmock.NewRows(columns).AddRow("tidb_txn_mode", "optimistic"),
-	)
-	mock.ExpectQuery("select version\\(\\);").WillReturnRows(
-		sqlmock.NewRows([]string{"version"}).AddRow("5.7.25-TiDB-v5.0.0"),
-	)
 	mock.ExpectClose()
 	return db, nil
 }