A global database network (GDN) consists of multiple PolarDB clusters that are deployed in multiple regions around the world. This topic describes the details of the GDN, such as its features.

Introduction

In GDNs, data in all clusters is synchronized. Each cluster in the network provides read and write services and geo-disaster recovery capabilities. GDNs apply to the following scenarios:

  • Active geo-redundancy

    Traditionally, if your service is deployed in multiple regions, the database is deployed in the primary region. Applications in other regions need to access the database in the primary region across regions. This causes a network latency and compromises the performance and user experience. GDNs have the following features: low-latency synchronization across regions, cross-region read/write splitting, and local or nearby reading. These features ensure that the latency is less than 2 seconds when applications in all regions 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 encounters a region-level failure, your service is automatically switched to the secondary cluster for a quick recovery.

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Features

  • Low-latency synchronization across regions: Multi-channel physical replication is used so that the latency of global synchronization is less than 2 seconds under heavy loads. For more information, see Cross-region deployment.
  • Cross-region read/write splitting and nearby reading: All clusters in GDNs are readable and writable. Read requests are directly sent to the local cluster. 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 a GDN.
  • Low-latency synchronization across regions: GDNs reduce the latency of the cross-region replication between primary and secondary clusters by using technologies, such as physical logs and parallel processing. Data is synchronized among all the clusters and the network latency is within 2 seconds. For more information, see Low-latency synchronization across regions.

Pricing

The cross-region data transfer traffic within a GDN is free. You are charged for only each PolarDB cluster that uses the GDN feature. For more information about the pricing of PolarDB clusters, see Billable items.

Supported regions and cluster versions

  • Regions: GDNs are available in more than 10 regions around the world, including mainland China, China (Hong Kong), and regions outside China.
  • Cluster versions: Only PolarDB for MySQL 8.0.1 Cluster Edition is supported.

Get started

For more information, see Create a GDN.

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GDN

References