All Products
Document Center

PolarDB:Enable X-Engine

Last Updated:Apr 22, 2024

This topic describes the prerequisites, usage notes, and procedure for enabling X-Engine in a PolarDB cluster.


  • The Database Edition of the PolarDB cluster is Enterprise Edition. The Edition of the cluster is Cluster Edition. The cluster is of PolarDB for MySQL 8.0 and the revision version is:

    • or later;

    • or later.

    For information about how to check the cluster version, see Query an engine version.

  • The primary node of the PolarDB cluster has at least 8 GB of memory. The specifications of the read-only nodes in the cluster must be higher than or the same as those of the primary node.

  • The PolarDB cluster has not joined a global database network (GDN).

Usage notes

  • After X-Engine is enabled for a PolarDB cluster, you cannot disable this feature. Otherwise, access exceptions may occur to tables stored in the X-Engine.

  • After X-Engine is enabled for a PolarDB cluster, the cluster cannot join a GDN.

  • When you enable X-Engine, your clusters are automatically restarted, which causes a disconnection that can last up to 30 seconds. We recommend that you perform this operation during off-peak hours and make sure that your applications can automatically reconnect to the database service.


You can use one of the following methods to enable X-Engine:

Method 1: Enable X-Engine for an existing cluster

  1. Log on to the PolarDB console.

  2. In the left-side navigation pane, click Clusters.

  3. In the upper-left corner of the console, select the region in which the cluster that you want to manage is deployed.

  4. Find the cluster and click the cluster ID.

  5. In the left-side navigation pane, choose Settings and Management > Data Lifecycle. Click the X-Engine (Warm Data) tab.


  6. Click Enable.

  7. In the Set X-Engine Proportion dialog box, configure the data and memory usage ratio for X-Engine based on your actual business scenarios and then click Enable.

    The following table provides the recommended proportion for three typical scenarios. You can set your proportion based on your business requirements.


    InnoDB (%)

    X-Engine (%)

    Use InnoDB for hot data and X-Engine for cold data. The cold data is classified as seldom accessed.



    Use InnoDB for hot data and X-Engine for cold data. The cold data is still updated and can be queried.



    Use InnoDB for small amounts of data and X-Engine for large amounts of data that require to be updated or queried.



  8. In the Confirm message, click OK.

Method 2: Select X-Engine as the storage engine when you purchase a cluster

For more information, see Select a Storage Type in Purchase a pay-as-you-go cluster and Purchase a subscription cluster.