A global database network (GDN) consists of multiple PolarDB clusters that are deployed in multiple regions around the world. This topic describes GDNs and their features.
Data is synchronized among clusters in each GDN. Each cluster in the network provides read and write services and geo-disaster recovery capabilities. GDNs are suitable for the following scenarios:
- Active geo-redundancy
If you run services in multiple regions and deploy databases in a central region, global applications have to access the central databases across regions with high latency. This may result in poor performance. GDNs use an asynchronous replication mechanism to replicate data across regions with low latency. GDNs also support cross-region read/write splitting and forward read requests to the clusters that are deployed in the same region as the application. This ensures a network latency of less than 2 seconds when applications access the database.
- Geo-disaster recovery
GDNs support geo-disaster recovery regardless of whether your service is deployed in one or more regions. If the primary cluster fails in a region, you need to switch your service to the secondary cluster.
- No need to modify the code: You can directly deploy services from one region to multiple regions. For more information, see Cross-region deployment.
- Cross-region read/write splitting: Each cluster in a GDN is in a read and write mode. Read requests are sent to the cluster in the same region. Write requests are forwarded to the primary cluster. For more information, see Cross-region read/write splitting.
- Flexible configuration: The primary and secondary clusters have independent configurations, such as cluster specifications, whitelists, and parameter values. For more information, see Create and release a GDN.
- Low-latency synchronization across regions: Multi-channel physical replication is used. This way, the latency of data synchronization in a GDN is less than 2 seconds during heavy loads. For more information, see Low-latency synchronization across regions.
Cross-region data transmission within a GDN is free of charge. You are charged only for PolarDB clusters in the GDN. For more information about the pricing rules of PolarDB clusters, see Billable items.
Supported regions and clusters
- Regions: GDNs are available in more than 10 regions, which include regions in mainland China, the China (Hong Kong) region, and regions outside China.
- Clusters in a GDN must meet the following requirements:
- The edition of the cluster is Cluster Edition.
- The version of the cluster is ApsaraDB PolarDB MySQL-compatible edition 8.0.
Get started with GDNs
For more information, see Create and release a GDN.