You can temporarily upgrade the specifications of a PolarDB cluster or a single node in a PolarDB cluster. When the specified scale-back time is reached, the cluster is automatically scaled back to the original specifications. For a subscription PolarDB cluster, you can temporarily upgrade the specifications of the cluster to meet the business peak requirements in the specified validity period of the temporary upgrade.
Prerequisites
- The cluster is a subscription cluster.
- The cluster does not have pending renewal, upgrade, downgrade, or temporary upgrade orders.
Usage notes
- PolarDB clusters do not support temporary downgrades.
- When PolarDB temporarily scales up or back a cluster, transient connections to the cluster may occur. Make sure that your application can automatically reconnect to the cluster.
- The scale-back time must be at least one day before the expiration date of the cluster. For example, if a cluster expires on January 10, the scale-back time cannot be later than January 9.
- If a cluster is temporarily upgraded, you cannot add nodes to the cluster or remove nodes from the cluster. In addition, the cluster does not support automatic scaling. For more information about how to add or remove nodes, see Add or remove a read-only node. If you want to perform manual horizontal scaling or use automatic scaling when the temporary upgrade is still effective, you must permanently upgrade the cluster. For more information, see the "Permanently retain the temporarily upgraded specifications" section of this topic.
- When the temporary upgrade remains effective (the cluster is in the running state), you can perform manual upgrades. For more information about how to manually upgrade a cluster, see Change the specifications of a PolarDB cluster.
- The minimum validity period for a temporary upgrade is 1 hour. We recommend that you set the validity period of a temporary upgrade to no more than 14 days.
- After you perform a temporary upgrade, if the cluster still does not meet your business requirements or you want to extend the validity period of the temporary upgrade, you can perform another temporary upgrade before the first temporary upgrade becomes ineffective. The scale-back time of the second temporary upgrade must not be earlier than that of the first temporary upgrade.
Permanently retain the temporarily upgraded specifications
Select different specifications for the primary node and read-only nodes
For a PolarDB cluster, you can perform separate temporary upgrades for the primary node and read-only nodes. This means that you can select different specifications for the primary node and read-only nodes.
Limits
- In a cluster, at least one read-only node must have the same specifications as the primary node.
- We recommend that you select similar specifications for the primary node and read-only
nodes:
- The memory of a read-only node cannot be less than half of the memory of the primary node.
- The following table lists the correspondence of CPU specifications for the primary
node and read-only nodes.
CPU cores for the primary node Minimum CPU cores for read-only nodes 2 2 4 4 8 4 16 8 32 16 64 32 88 32
Billing
The fee of a temporary upgrade is 1.5 times the price difference between the original and new specifications. For example, assume that the validity period of a temporary upgrade is N days. You can calculate the temporary upgrade fee by using the following formula:
Temporary upgrade fee = (Monthly subscription fee for the new specifications - Monthly subscription fee for the original specifications)/30 × 1.5 × N