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    PolarDB:Add or Remove Nodes

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    PolarDB:Add or Remove Nodes

    Last Updated:Mar 30, 2026

    PolarDB-X is a distributed cluster that scales horizontally by adding or removing nodes. Use this procedure to change the number of nodes in your PolarDB-X instance.

    Prerequisites

    Before you begin, make sure that you have:

    • A PolarDB-X instance running the Enterprise Edition

    • The required instance version:

      • Version 2.4.0: polardb-2.4.0_5.4.19-20250923_xcluster5.4.20 or later

      • Version 2.5.0: polardb-2.5.0_5.4.20-20251022_xcluster8.4.20-20250908 or later

    For version details, see Release notes. If your instance version is earlier than required, upgrade it before proceeding. Validate SQL compatibility on a test instance running the target version before upgrading production.

    Potential impacts

    Adding or removing storage nodes triggers a data migration and an automatic data balancing task. The data balancing task consumes CPU and I/O resources on storage nodes and may affect performance during execution.

    Warning

    Data migration occurs during node changes. Long-running transactions that take more than 15 seconds to complete may be interrupted by metadata changes during the migration. Perform this operation during your operations and maintenance (O&M) window.

    To prevent data balancing from running during peak hours, configure an O&M window to schedule the task. See Configure the O&M window for scaling data balancing.

    Before removing nodes, also review the following:

    Warning

    Removing nodes reduces the maximum payload your instance can handle. Assess whether the remaining capacity meets your business needs before confirming.

    Warning

    Historical backup sets become invalid after you remove storage nodes. Back up your data immediately after the operation completes.

    Add or remove nodes

    1. Log on to the PolarDB-X console.

    2. In the top navigation bar, select the region where the instance is deployed.

    3. On the Instances page, click the PolarDB-X 2.0 tab.

    4. In the Actions column of the target instance, click Add Node or Remove Node.

    5. On the page that appears, specify the number of nodes to add or remove.

    6. Click Buy Now.

    7. In the dialog box that appears, click Sign and Place Order.

    After the operation completes, the instance status in the console changes to Adding Nodes or Removing Nodes.

    Billing

    Adding nodes is a paid operation. Removing nodes is free of charge.

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