address comment

v4/export/dump.go

@@ -852,11 +852,11 @@ func extractTiDBRowIDFromDecodedKey(indexField, key string) (string, error) {
 }
 
 func getListTableTypeByConf(conf *Config) listTableType {
-	// use listTableByInfoSchema by default because it has more accurate information
-	listType := listTableByInfoSchema
+	// use listTableByShowTableStatus by default because it has better performance
+	listType := listTableByShowTableStatus
 	if conf.Consistency == consistencyTypeLock {
 		// for consistency lock, we need to build the tables to dump as soon as possible
-		listType = listTableByShowTableStatus
+		listType = listTableByInfoSchema
 	} else if conf.Consistency != consistencyTypeNone && matchMysqlBugversion(conf.ServerInfo) {
 		// For some buggy versions of mysql, we need a workaround to get a list of table names.
 		listType = listTableByShowFullTables

v4/export/dump_test.go

@@ -91,21 +91,22 @@ func (s *testSQLSuite) TestDumpTableMeta(c *C) {
 
 func (s *testSQLSuite) TestGetListTableTypeByConf(c *C) {
 	conf := defaultConfigForTest(c)
+	tctx := tcontext.Background().WithLogger(appLogger)
 	cases := []struct {
 		serverInfo  ServerInfo
 		consistency string
 		expected    listTableType
 	}{
-		{ParseServerInfo(tcontext.Background(), "5.7.25-TiDB-3.0.6"), consistencyTypeSnapshot, listTableByInfoSchema},
+		{ParseServerInfo(tctx, "5.7.25-TiDB-3.0.6"), consistencyTypeSnapshot, listTableByShowTableStatus},
 		// no bug version
-		{ParseServerInfo(tcontext.Background(), "8.0.2"), consistencyTypeLock, listTableByShowTableStatus},
-		{ParseServerInfo(tcontext.Background(), "8.0.2"), consistencyTypeFlush, listTableByInfoSchema},
-		{ParseServerInfo(tcontext.Background(), "8.0.23"), consistencyTypeNone, listTableByInfoSchema},
+		{ParseServerInfo(tctx, "8.0.2"), consistencyTypeLock, listTableByInfoSchema},
+		{ParseServerInfo(tctx, "8.0.2"), consistencyTypeFlush, listTableByShowTableStatus},
+		{ParseServerInfo(tctx, "8.0.23"), consistencyTypeNone, listTableByShowTableStatus},
 
 		// bug version
-		{ParseServerInfo(tcontext.Background(), "8.0.3"), consistencyTypeLock, listTableByShowTableStatus},
-		{ParseServerInfo(tcontext.Background(), "8.0.3"), consistencyTypeFlush, listTableByShowFullTables},
-		{ParseServerInfo(tcontext.Background(), "8.0.3"), consistencyTypeNone, listTableByInfoSchema},
+		{ParseServerInfo(tctx, "8.0.3"), consistencyTypeLock, listTableByInfoSchema},
+		{ParseServerInfo(tctx, "8.0.3"), consistencyTypeFlush, listTableByShowFullTables},
+		{ParseServerInfo(tctx, "8.0.3"), consistencyTypeNone, listTableByShowTableStatus},
 	}
 
 	for _, x := range cases {

v4/export/sql.go

@@ -215,23 +215,20 @@ func ListAllDatabasesTables(tctx *tcontext.Context, db *sql.Conn, databaseNames
 			dbTables[schema] = make([]*TableInfo, 0)
 			query := fmt.Sprintf("SHOW FULL TABLES FROM `%s` WHERE %s",
 				escapeString(schema), strings.Join(tableTypeConditions, " OR "))
-			rows, err := db.QueryContext(tctx, query)
-			if err != nil {
-				return nil, errors.Annotatef(err, "sql: %s", query)
-			}
-			results, err := GetColumnValuesAndIgonreColumnName(rows)
-			if err != nil {
-				return nil, errors.Annotatef(err, "sql: %s", query)
-			}
-			for _, oneRow := range results {
-				table = oneRow[0]
-				avgRowLength = 0 // can't get avgRowLength from the result of `show full tables` so hardcode to 0 here
+			if err = simpleQueryWithArgs(db, func(rows *sql.Rows) error {
 				var err2 error
-				tableType, err2 = ParseTableType(oneRow[1])
+				if err2 = rows.Scan(&table, &tableTypeStr); err != nil {
+					return errors.Trace(err2)
+				}
+				tableType, err2 = ParseTableType(tableTypeStr)
 				if err2 != nil {
-					return nil, errors.Trace(err2)
+					return errors.Trace(err2)
 				}
+				avgRowLength = 0 // can't get avgRowLength from the result of `show full tables` so hardcode to 0 here
 				dbTables[schema] = append(dbTables[schema], &TableInfo{table, avgRowLength, tableType})
+				return nil
+			}, query); err != nil {
+				return nil, errors.Annotatef(err, "sql: %s", query)
 			}
 		}
 	default:
@@ -583,39 +580,6 @@ func GetSpecifiedColumnValuesAndClose(rows *sql.Rows, columnName ...string) ([][
 	return strs, errors.Trace(rows.Err())
 }
 
-// GetColumnValuesAndIgonreColumnName get columns' values and ignore column name
-func GetColumnValuesAndIgonreColumnName(rows *sql.Rows) ([][]string, error) {
-	if rows == nil {
-		return [][]string{}, nil
-	}
-	defer rows.Close()
-	results := [][]string{}
-	columns, err := rows.Columns()
-	if err != nil {
-		return nil, errors.Trace(err)
-	}
-	columnsLen := len(columns)
-	addr := make([]interface{}, columnsLen)
-	oneRow := make([]sql.NullString, columnsLen)
-	for i := range columns {
-		addr[i] = &oneRow[i]
-	}
-	for rows.Next() {
-		err := rows.Scan(addr...)
-		if err != nil {
-			return nil, errors.Trace(err)
-		}
-		tmpStr := make([]string, columnsLen)
-		for i, val := range oneRow {
-			if val.Valid {
-				tmpStr[i] = val.String
-			}
-		}
-		results = append(results, tmpStr)
-	}
-	return results, errors.Trace(rows.Err())
-}
-
 // GetPdAddrs gets PD address from TiDB
 func GetPdAddrs(tctx *tcontext.Context, db *sql.DB) ([]string, error) {
 	query := "SELECT * FROM information_schema.cluster_info where type = 'pd';"