PolarDB:Create and manage a global database network

Requirements and limitations

Pricing

Charges for a Global Database Network (GDN) consist of the cluster costs and any applicable cross-border data replication fees. The billing rules are as follows:

• Free scenarios:

  Your primary and secondary clusters are both deployed in regions within the Chinese mainland, or both are deployed in the China (Hong Kong) region or other overseas regions. Examples:

  • Both the primary and secondary clusters are in the Chinese mainland. For example, the primary cluster is in China (Chengdu) and the secondary clusters are in regions such as China (Hangzhou) or China (Shenzhen).

  • Both the primary and secondary clusters are in the China (Hong Kong) region or other overseas regions. For example, the primary cluster is in Singapore and the secondary cluster is in Philippines (Manila).

• Billable scenarios:

  Cross-border fees apply when a GDN spans the Chinese mainland border—for example, if one cluster is in the Chinese mainland and another is in China (Hong Kong) or an overseas region. Examples:

  • The primary cluster is in the Chinese mainland and the secondary cluster is outside the Chinese mainland. For example, the primary cluster is in China (Chengdu) and the secondary cluster is in a region such as China (Hong Kong) or Singapore.

  • The primary cluster is outside the Chinese mainland and the secondary cluster is in the Chinese mainland. For example, the primary cluster is in Singapore and the secondary cluster is in a region such as China (Hangzhou) or China (Shenzhen).

• Billing rule: USD 0.80 per GB, billed hourly. The fee is calculated hourly based on the volume of redo log data physically replicated from the primary cluster to a cross-border secondary cluster. This traffic fee can be estimated by querying the physical position converted from the log sequence number (LSN).

  Billing example

  Example

  At 09:00, you query the physical write position of the log and find it is ib_logfile1/648143676. At 10:00, the position is updated to ib_logfile3/648142342. The amount of data written in this hour is the difference between the two positions.

  1. Amount written to the start file (ib_logfile1):
     Subtract the start offset from the total file size. Each log file is 1 GB (1,073,741,824 bytes). The amount written is 1073741824 - 648143676 = 425598148 bytes.
     
     
     
     

  2. Amount written to the intermediate file (ib_logfile2):
     After ib_logfile1 is full, the system completely writes ib_logfile2. This amount is 1,073,741,824 bytes (1 GB).
     
     
     
     

  3. Amount written to the end file (ib_logfile3):
     This is the offset at the end, which is 648142342 bytes.
     
     
     
     

  Therefore, the total amount written is 425598148 + 1073741824 + 648142342 = 2147482314 bytes. This is 2147482314 / 1024 / 1024 / 1024 = 1.999998 GB (rounded down to six decimal places). The cross-border data transfer fee for this hour is approximately 1.999998 GB × USD 0.80/GB = USD 1.5999984.

  Query the log write progress and physical file offset

  -- Query the current write progress of the log system.
  SHOW STATUS LIKE 'Innodb_log_write_lsn'; 
  +----------------------+------------+
  | Variable_name        | Value      |
  +----------------------+------------+
  | Innodb_log_write_lsn | 1721889596 |
  +----------------------+------------+
  
  -- Query the physical file offset in bytes.
  SELECT lsn_to_pos(1721889596); 
  +------------------------+
  | lsn_to_pos(1721889596) |
  +------------------------+
  | ib_logfile1/648143676  |
  +------------------------+

Create a global database network

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

2. On the GDN page, click Create GDN.

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

   Parameter	Description
   Compatibility	Select MySQL.
   Version	This is set to Active-passive and cannot be changed.
   Name:	The name of the GDN. Enter a descriptive name for easy identification. The name does not need to be unique.
   Primary Region	Select the region where the primary cluster is located. Note First, determine which cluster you want to use as the primary cluster, and then select the region where that cluster is located.
   Primary Cluster:	Select an existing cluster as the primary cluster of the GDN.
   Global Domain Name	Specifies whether to enable the global domain name. This feature provides a unified endpoint for the GDN. A global domain name not only enables proximity-based access but also ensures that the endpoint remains unchanged after a primary cluster switchover.

4. Click OK. You can view the created GDN on the GDN page. You can then add a secondary cluster to the GDN.

View global database network information

Go to the PolarDB console. On the GDN page, click a GDN ID to view its details. The details page displays the basic information, cluster list, and network topology of the GDN.

Delete a global database network

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

2. On the GDN page, find the target GDN and click Delete in the Actions column.

   Note

   If the Delete button is grayed out, the GDN still contains secondary clusters. You must delete the secondary clusters before you can delete the GDN.

3. Carefully read the notes in the dialog box that appears. After you confirm the information, click OK to delete the GDN.

References

• Add and manage a secondary cluster: Describes how to add a secondary cluster to a global database network (GDN).

• Connect to a global database network: Explains how to establish application connections to a GDN.

• Create a global domain name: Describes how to create a unified endpoint that enables proximity-based access and remains unchanged after a primary cluster switchover.

API reference

FAQ