This topic describes the components of the PolarDB engine version and the relationship between the components, and how to query and upgrade the engine version.

The following figure shows the position of the PolarDB database engine in the PolarDB architecture. 1

For more information about the architecture and features of PolarDB, see Architecture.

Components of the engine version and their relationship

A complete engine version of PolarDB consists of three parts: DB version, minor version, and revision version. The following figure shows the relationship among the three parts. In the following example, the DB version of PolarDB for MySQL is 8.0.Components of the engine version

The DB version is the most important part that is used to identify an engine version of PolarDB. The DB version has one or more minor versions. For example, DB version 5.6 has only minor version 5.6.16, and DB version 8.0 has two minor versions of 8.0.1 and 8.0.2. Features vary based on minor versions. We recommend that you select a minor version based on your business requirements before you purchase a cluster. In most cases, a minor version has multiple revision versions. A revision version optimizes or improves existing features, or adds new features. In minor versions and revision versions, security and performance are improved.

Note The latest engine version of PolarDB is compatible with earlier versions and includes all the features of the earlier versions. Therefore, you do not need to modify your applications after you upgrade engine versions. For more information about how to upgrade the engine version, see Update the engine version.

Query the engine version

You can use the following methods to query the engine version number of a cluster:

  • Log on to the PolarDB console. On the Overview page of the cluster whose engine version number you want to query, check the value of the Kernel Version parameter. 1
  • Execute the show variables like "%polardb_version%"; or show variables like '%rds_release_date%'; statement to query the engine version.
    Note
    • You can execute only the show variables like '%rds_release_date%'; statement to query the engine version of a PolarDB for MySQL 5.6 cluster.
    • For more information about the components of the PolarDB engine version, see Components of the engine version and their relationship.

Update the engine version

  • Upgrade major versions and minor versions

    PolarDB does not allow you to upgrade the major versions or the minor versions in a direct way. For example, you cannot upgrade PolarDB for MySQL 5.6 to PolarDB for MySQL 8.0 or upgrade the minor version from PolarDB for MySQL 8.0.1 to 8.0.2 in a direct way. However, you can use Data Transmission Service (DTS) to migrate or synchronize data from the cluster of the source version to the cluster of the destination version. For more information about how to migrate or synchronize data, see Overview of data migration or synchronization solutions.

  • Upgrade revision versions

    For more information about how to upgrade revision versions, see Upgrade the revision version.