After you create a Global Database Network (GDN), you can add secondary clusters to it for cross-region replication and disaster recovery. When a secondary cluster is no longer needed, remove it from the GDN — it then becomes a standalone, read/write PolarDB cluster.
Prerequisites
Before you begin, make sure you have:
Created a GDN. For instructions, see .
Reviewed the supported regions and limits below.
Supported regions
GDN is available in more than 10 regions worldwide.
| Primary cluster region | Supported secondary cluster regions |
|---|---|
| Any region in the Chinese mainland | The same region as the primary cluster, or any other region in the Chinese mainland. For example, if the primary cluster is in China (Hangzhou), the secondary cluster can be in China (Hangzhou) or any other Chinese mainland region. For other region combinations, submit a ticket. |
| Any region outside the Chinese mainland | China (Hong Kong), Japan (Tokyo), South Korea (Seoul), Singapore, Malaysia (Kuala Lumpur), Indonesia (Jakarta), Philippines (Manila), Thailand (Bangkok), Germany (Frankfurt), US (Silicon Valley), US (Virginia), UK (London) |
For regions outside the Chinese mainland, sign the Cross-Border Data Transfer Compliance Agreement before creating a secondary cluster.
Limits
| Category | Limit |
|---|---|
| Unsupported features | Serverless and In-Memory Column Index (IMCI) are not supported in GDN clusters. |
| Unsupported operations | Database and table restoration is not supported in GDN clusters. |
| Cluster count | One primary cluster and up to four secondary clusters per GDN. |
| Database engine | All clusters in the same GDN must run PostgreSQL 14. |
| Node specifications | Secondary cluster node specifications must be greater than or equal to those of the primary cluster. Keep specifications consistent when possible. |
| GDN membership | A cluster can belong to only one GDN. |
Add a secondary cluster
Log on to the PolarDB console. In the left navigation pane, click Global Database Network (GDN).
On the Global Database Network (GDN) page, find the target GDN and click Add Secondary Cluster in the Actions column.
On the purchase page, configure the following parameters. For all other parameters, see .
Parameter Description Region Select a region. For supported regions, see Supported regions. Creation method Select Create Secondary Cluster. Global Database Network Select the target GDN. The GDN you selected in the previous step is pre-selected. Database engine Must match the primary cluster: PostgreSQL 14. Compute node specifications Must be greater than or equal to the primary cluster specifications. To use higher specifications, upgrade the secondary cluster after it is created. After the purchase completes, return to the Global Database Network (GDN) page. Click the Global Database Network ID of the target GDN to open its details page. The new secondary cluster appears in the Clusters section.
Remove a secondary cluster
When you remove a secondary cluster from a GDN, data synchronization between it and the primary cluster stops, and the cluster switches to read/write mode as a standalone PolarDB cluster.
A cluster removed from a GDN cannot be added back to any GDN as a secondary cluster. This action is irreversible.
Log on to the PolarDB console. In the left navigation pane, click Global Database Network (GDN).
On the Global Database Network (GDN) page, find the target GDN and click its Global Database Network ID to open the details page.
In the Clusters section, find the secondary cluster to remove and click Remove in the Actions column.
Only secondary clusters can be removed. The primary cluster cannot be removed from a GDN.
In the dialog box, read the notes carefully and click OK.
What to expect during removal:
The removal process takes about 5 minutes.
During removal, the endpoints of all clusters in the GDN — including the cluster being removed — remain available. Applications can continue accessing the databases through cluster endpoints.
Switch the primary cluster
Use this operation for planned maintenance or regional failover drills. Forced switchover is not supported.
Before you switch:
Check internet endpoints. If the current primary cluster has an internet endpoint, make sure the new primary cluster also has one. Otherwise, applications that rely on the internet endpoint will lose access. To apply for an endpoint, see .
Schedule during off-peak hours. The switchover causes a transient connection break of about 160 seconds.
Verify automatic reconnection. Make sure your application has an automatic reconnection mechanism before you proceed.
Steps:
Log on to the PolarDB console. In the left navigation pane, click Global Database Network (GDN).
On the Global Database Network (GDN) page, find the target GDN and click its Global Database Network ID to open the details page.
In the Clusters section, find the target secondary cluster and click Switch To Primary Cluster in the Actions column.
In the Primary/Secondary Switchover dialog box, select the secondary cluster to promote as the new primary cluster and click OK.
See also
— GDN architecture and common use cases.
Connect to a GDN — Connect your applications to a GDN.
API reference
| API | Description |
|---|---|
| CreateDBCluster | Add a secondary cluster to a GDN. Set CreationOption to CreateGdnStandby and provide the GDNId. |
| RemoveDBClusterFromGDN | Remove a secondary cluster from a GDN. |
| SwitchOverGlobalDatabaseNetwork | Switch the primary cluster of a GDN. |