A PolarDB-X instance is a distributed cluster that consists of multiple nodes. PolarDB-X allows you to scale out or scale in an instance by adding or removing nodes.
Edition requirements
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Only the Enterprise Edition is supported.
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Instance version requirements:
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Version 2.4.0: polardb-2.4.0_5.4.19-20250923_xcluster5.4.20 or later.
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Version 2.5.0: polardb-2.5.0_5.4.20-20251022_xcluster8.4.20-20250908 or later.
Note-
For rules on instance versions, see Kernel release notes.
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To view the instance version, see View and update the engine version of a PolarDB for Xscale instance.
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If the instance version is earlier than the target version, you can upgrade to the latest version to support adding or removing nodes. We recommend that you perform comprehensive validation on an instance running the target version before upgrading to avoid SQL compatibility issues.
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Procedure
Log on to the PolarDB-X console.
In the top navigation bar, select the region where the instance is deployed.
On the Instances page, click the PolarDB-X 2.0 tab.
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In the Actions column of the target instance, click Add Node or Remove Node.
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On the page that appears, specify the number of nodes to add or remove.
Warning-
Data migration is involved when you add or remove storage nodes. Perform this operation during your O&M window. Long-running transactions that take more than 15 seconds to complete may be interrupted during the metadata changes of data migration.
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Removing nodes reduces the maximum load capacity of the instance. Evaluate and confirm that the remaining capacity is sufficient for your business needs.
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Historical backup sets become invalid after you remove storage nodes. We recommend that you back up data immediately after the removal succeeds.
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When you add or remove storage nodes, an automatic data balancing task is triggered on the storage nodes. The task consumes some CPU and I/O resources on the storage nodes and may degrade business performance. Therefore, PolarDB-X provides a configurable O&M window to help you schedule the data balancing task and prevent it from running during business peak hours. For more information, see Configure a maintenance window for data rebalancing.
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Click Buy Now.
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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.
NoteAdding nodes incurs fees. Removing nodes is free of charge.