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PolarDB:Create a GDN

Last Updated:May 13, 2025

A global database network (GDN) consists of multiple PolarDB clusters that are deployed in multiple regions. Data is replicated across all clusters in each GDN. This allows applications that are deployed across different regions to access a database that is local to their region, which provides reliable access with low latency. This topic describes how to create and release a GDN.

Prerequisites

A PolarDB cluster is created as the primary cluster in a GDN.

Supported regions and clusters

  • Regions: GDN is available in more than 10 regions, including regions inside the Chinese mainland, the China (Hong Kong) region, and regions outside China. For more information, see Region mappings between the primary and secondary clusters.

  • Clusters:

    • Database Edition is Enterprise Edition, and Edition is Cluster Edition.

    • Database Engine:

      • MySQL 8.0.2.

      • MySQL 8.0.1 with revision version 8.0.1.1.17 or later.

      • MySQL 5.7 with revision version 5.7.1.0.21 or later.

      • MySQL 5.6 with revision version 5.6.1.0.32 or later.

  • The following limits also apply:

    • A GDN consists of one primary cluster and up to four secondary clusters.

      Note

      To add more secondary clusters, go to Quota Hub, find the quota item based on the quota ID polardb_mysql_gdn_region, and click Apply in the Actions column.

    • The primary cluster and secondary clusters must use the same database engine version. Supported versions are MySQL 8.0, MySQL 5.7, and MySQL 5.6.

    • A cluster belongs to only one GDN.

    • Clusters in a GDN can be serverless clusters or serverless-enabled clusters with defined specifications. When the database engine of the primary cluster meets the following conditions, all clusters in the GDN must have at least one read-only node.

      • PolarDB for MySQL 8.0.1 with revision version 8.0.1.1.42 or later.

      • PolarDB for MySQL 8.0.2 with revision version 8.0.2.2.23 or later.

    • For non-serverless secondary clusters in a GDN, each compute node must have at least 4 CPU cores.

    • Clusters in a GDN do not support the database and table restoration feature.

    • Clusters in a GDN support the in-memory column index (IMCI) feature. However, before you add read-only IMCI nodes to a cluster, you must contact us to enable GDN support for IMCI by adding the feature to whitelists.

Usage notes

If you want to create a secondary cluster in a region outside Chinese mainland for a GDN, you must sign the PolarDB Cross-border Data Transfer Compliance Commitment.

  • The following table lists the region mappings between the primary and secondary clusters in a GDN.

    Region of the primary cluster

    Region of the secondary cluster

    All regions in Chinese mainland

    In the same region as the primary cluster or in a region in Chinese mainland other than the region where the primary cluster is deployed.

    For example, if the primary cluster is in the China (Hangzhou) region, secondary clusters can be in the China (Hangzhou) region or other regions in Chinese mainland.

    Note

    If you want to deploy the secondary cluster in other regions, contact us.

    Regions outside 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).

Pricing

You are not charged for the traffic that is generated during cross-region data transmission within a GDN. You are charged only for the use of PolarDB clusters in the GDN. For more information, see Billing.

Create a GDN

  1. Log on to the PolarDB console. In the left-side navigation pane, click Global Database Network.

  2. On the Global Database Network page, click Create GDN.

    1

  3. In the Create GDN dialog box, configure the following parameters.

    Parameter

    Description

    Name

    The name of the GDN that you want to create. We recommend that you specify a descriptive name that makes it easy to identify. GDN names do not have to be unique.

    Primary Region

    The region where the primary cluster is deployed.

    Note

    Select the region where the primary cluster is deployed.

    Primary Cluster

    Select an existing cluster as the primary cluster of the GDN.

  4. After you create a GDN, you can add secondary clusters. For more information, see Manage a secondary cluster.

Release a GDN

    Log on to the PolarDB console. In the left-side navigation pane, click Global Database Network.

  1. Find the GDN that you want to release and click Delete in the Actions column.

    Important
    • A GDN can be released if it contains only the primary cluster.

    • A GDN cannot be restored after it is released. Proceed with caution.

    • Applications that are connected to the endpoints of a GDN cannot access databases after the GDN is released. Modify the application code to change the connection string of the GDN at the earliest opportunity.

FAQ

How many GDNs can I create for an Alibaba Cloud account?

The number of GDNs that you can create is unlimited.

After a GDN is created, can I change the primary cluster of the GDN?

No, you cannot change the primary cluster of the GDN after the GDN is created. You can create another GDN, select the required cluster as the primary cluster, and then release the current GDN.

Note

Before you release the GDN, remove all secondary clusters from the GDN.

References

Related API operations

Operation

Description

CreateGlobalDatabaseNetwork

Creates a GDN

DeleteGlobalDatabaseNetwork

Deletes a GDN.

DescribeGlobalDatabaseNetwork

Queries the information about a GDN.