Engine versions 5.6, 5.7, and 8.0

A PolarDB for MySQL engine version number consists of a major version, a minor version, and a revision. The following figure illustrates this structure using PolarDB for MySQL 8.0 as an example:

Each engine version has release notes that list its new features, enhancements, and bug fixes. For more information, see the following topics:

• PolarDB for MySQL 8.0.2 release notes

• PolarDB for MySQL 8.0.1 release notes

• PolarDB for MySQL 5.7 release notes

• PolarDB for MySQL 5.6 release notes

The PolarDB for MySQL engine is compatible with the following:

• ANSI/ISO SQL standard. PolarDB for MySQL lets you change the SQL compatibility mode to ANSI. To do this, set the sql_mode cluster parameter to ANSI. To learn how to modify cluster parameters, see Set cluster and node parameters.

• ODBC versions 0 to 3.51.

• XML features that follow W3C and XPath standards.

• PolarDB for MySQL 5.7 and 8.0 support the native JSON data type as defined by RFC 7159 and ECMA-262.

The following table shows the compatibility of PolarDB for MySQL engine versions with community MySQL versions.

For CREATE TABLE syntax, compatibility is automatically ensured by adding specific syntax during operations like SHOW CREATE TABLE, when using the mysqldump tool, or when synchronizing the binary log. The following examples provide more details:

• The required compatibility syntax is automatically included in the output of SHOW CREATE TABLE. Example:

  CREATE TABLE `t1` (c1 int, KEY(c1) GLOBAL) ENGINE=InnoDB PARTITION BY HASH (`c1`) PARTITIONS 4;
  Query OK, 0 rows affected (0.06 sec)
  SHOW CREATE TABLE t1;
  +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
  | Table | Create Table                                                                                                                                                                                                         |
  +-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
  | t1    | CREATE TABLE `t1` (
    `c1` int(11) DEFAULT NULL,
    KEY `c1` (`c1`) /*!99990 800020207 GLOBAL */
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
  /*!50100 PARTITION BY HASH (`c1`)
  PARTITIONS 4 */ |

• The mysqldump tool automatically includes the required compatibility syntax in its output. Example:

  CREATE TABLE `t1` (c1 int, KEY(c1) GLOBAL) ENGINE=InnoDB PARTITION BY HASH (`c1`) PARTITIONS 4;
  DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci PARTITION BY HASH (`c1`);
  --result
  mysqldump --compact test t1
  include/mysqlbinlog.inc
  /*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
  /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
  DELIMITER /*!*/;
  ROLLBACK/*!*/;
  # [empty]
  # original_commit_timestamp= MICROSECONDS-FROM-EPOCH (YYYY-MM-DD HOURS:MINUTES:SECONDS TZ)
  # immediate_commit_timestamp= MICROSECONDS-FROM-EPOCH (YYYY-MM-DD HOURS:MINUTES:SECONDS TZ)
  /*!80001 SET @@session.original_commit_timestamp= MICROSECONDS-FROM-EPOCH*//*!*/;
  /*!80014 SET @@session.original_server_version= ORIGINAL_SERVER_VERSION*//*!*/;
  /*!80014 SET @@session.immediate_server_version= IMMEDIATE_SERVER_VERSION*//*!*/;
  SET @@SESSION.GTID_NEXT= '#'/*!*/;
  use `test`/*!*/;
  SET TIMESTAMP=#/*!*/;
  SET @@session.pseudo_thread_id=#/*!*/;
  SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/;
  SET @@session.sql_mode=1168113696/*!*/;
  SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
  /*!\C utf8mb4 *//*!*/;
  SET @@session.character_set_client=255,@@session.collation_connection=255,@@session.collation_server=255/*!*/;
  SET @@session.lc_time_names=0/*!*/;
  SET @@session.collation_database=DEFAULT/*!*/;
  /*!80011 SET @@session.default_collation_for_utf8mb4=255*//*!*/;
  /*!80013 SET @@session.sql_require_primary_key=0*//*!*/;
  CREATE TABLE `t1` (
    `c1` int(11) DEFAULT NULL,
    KEY `c1` (`c1`) /*!99990 800020207 GLOBAL */
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
  /*!50100 PARTITION BY HASH (`c1`)
  PARTITIONS 4 */
  /*!*/;

• The required compatibility syntax is automatically added during binary log synchronization.

  This example shows binary log synchronization from PolarDB for MySQL 8.0.2.2.0 to MySQL 8.0.27:

  1. Use Data Transmission Service (DTS) to synchronize the binary log from PolarDB for MySQL to MySQL. For more information, see Synchronize data from PolarDB for MySQL to ApsaraDB RDS for MySQL.

  2. Check the binary log synchronization results on PolarDB for MySQL 8.0.2.2.0 and MySQL.

     Result in PolarDB for MySQL:

     root:test> show create table t6;
     +-------+--------------------------------------------------------------+
     | Table | Create Table                                                 |
     +-------+--------------------------------------------------------------+
     | t6    | CREATE TABLE `t6` (
       `a` int(11) DEFAULT NULL,
       `b` int(11) DEFAULT NULL
     ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
     /*!99990 800020200 PARTITION BY HASH (`a`)
     SUBPARTITION BY LIST (`b`)
     (PARTITION p0
      (SUBPARTITION s0 VALUES IN (1,2,3,4,5) ENGINE = InnoDB,
       SUBPARTITION s1 VALUES IN (6,7,8,9,10) ENGINE = InnoDB),
      PARTITION p1
      (SUBPARTITION s2 VALUES IN (1,2,3,4,5) ENGINE = InnoDB,
       SUBPARTITION s3 VALUES IN (6,7,8,9,10) ENGINE = InnoDB)) */ |
     +-------+--------------------------------------------------------------+
     1 row in set (4.72 sec)

     Result in MySQL:

     root:test> show create table t6;
     +-------+------------------------------------------------------------+
     | Table | Create Table                                               |
     +-------+------------------------------------------------------------+
     | t6    | CREATE TABLE `t6` (
       `a` int DEFAULT NULL,
       `b` int DEFAULT NULL
     ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
     +-------+------------------------------------------------------------+
     1 row in set (0.00 sec)

     As shown in the output, the result in MySQL does not include the new features from PolarDB for MySQL.

     Note

     After data synchronization from PolarDB for MySQL to MySQL, new features specific to PolarDB for MySQL are not available.

For DDL operations other than CREATE TABLE, you must manually add compatibility comments for PolarDB for MySQL syntax. Use the following format:

/*!99990 800020200 Special new PolarDB Syntax SQL supported >= version 2.2.0 */

Example:

CREATE TABLE `t1` (
`c1` int(11) DEFAULT NULL,
KEY `c1` (`c1`) /*!99990 800020207 GLOBAL */
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
/*!50100 PARTITION BY HASH (`c1`)
PARTITIONS 4 */