PolarDB:Add a read-only column store instance

Background information

The Clustered Columnar Index (CCI) feature of PolarDB-X adopts a component-based read/write splitting architecture. This architecture consists of two components: column store nodes and compute nodes. Column store nodes write row-oriented storage data and compute nodes read the data. Read-only column store instances can access the column-oriented data. These instances scale out different compute nodes to implement the physical isolation of CCI--based query traces and provide the same capabilities as read-only instances.

Usage notes

• The read-only column store instance and the primary instance are deployed in the same region but in different zones.

• The read-only column store instance cannot exist individually. The instance belongs to the primary instance. If you create a database in the primary instance, the database is replicated to each read-only instance that is associated with the primary instance. If you delete a database in the primary instance, the replicated database in each read-only instance that is associated with the primary instance is also deleted.

• The read-only column store instance is authorized only to access tables that contain CCIs. If the instance accesses tables that do not contain CCIs, an error message indicating query limits is reported.

Procedure

1. Log on to the PolarDB-X console.

2. In the top menu bar, select the region where the desired instance is deployed.

3. On the Instance List page, click the PolarDB-X 2.0 tab.

4. Find the instance and click Read-only Column Store Instance in the Actions column. You can also click the instance ID to go to the instance details page. In the Read-only Column Store Instance section of the instance details page, click Add Read-only Column Store Instance. ID

5. In the dialog box that appears, configure parameters described in the following table.

   Parameter	Description
   Billing Method	The billing method of the read-only column store instance. Valid values: Subscription and Pay-as-you-go. Note The subscription billing method allows you to use resources only after you pay for them. This billing method is suitable for long-term and stable use in production environments. The unit price of the subscription billing method is lower than that of the pay-as-you-go billing method. The pay-as-you-go billing method allows you to use resources before you pay for them. This billing method is suitable for testing and learning. If you want to create a pay-as-you-go PolarDB-X instance, make sure that the balance in your Alibaba Cloud account is at least USD 100.
   Region	The region where the read-only column store instance is deployed. The read-only column store instance and the primary instance must be deployed in the same region. For example, if the primary instance is deployed in the China (Hangzhou) region, this parameter is set to China (Hangzhou). You do not need to change the settings.
   Zone	The zone in which the read-only column store instance is deployed. The primary and the read-only column store instance can be deployed in different zones.
   Network Type	The network type of the read-only column store instance. Set the value to VPC. You cannot change the settings.
   VPC	The name of the Virtual Private Cloud (VPC).
   vSwitch	The name of the vSwitch.
   MySQL Version	The MySQL version of the read-only column store instance. Set the value to 5.7. You cannot change the settings.
   Instance Model	The model of the read-only column store instance. Set the value to Custom Model. You cannot change the settings.
   Instance Type	The instance family. Valid values: Standard and Dedicated.
   Compute Node Specifications	The specifications of compute nodes in the read-only column store instance. The specifications of the instance is calculated by using the following formula: Specifications of compute nodes × Number of compute nodes. You can configure this parameter to specify the number of CPU cores and memory size for the instance. Note Read-only column store instances contain only compute nodes. These instances do not contain row store nodes.
   Compute Nodes	The number of compute nodes in the read-only column store instance. Default value: 2.
   Storage Type	The storage type of the read-only column store instance. Set the value to Local SSD Disk. You cannot change the settings.
   Storage Cost	You are not charged for the storage of column store compute nodes. You do not need to specify capacity for the nodes.
   Duration	The subscription duration of the read-only column store instance. Note This parameter is valid only when the Billing Method parameter is set to Subscription.
   Quantity	The number of read-only column store instances that you want to purchase.

6. Read the terms of service, select Terms of Service, and then click Buy Now.

7. On the Purchase page, confirm the unpaid order and the payment method, and click Purchase.

8. After you complete the payment, it takes approximately 3 to 5 minutes to create the read-only column store instance. After the instance is created, you can go to the Instance List page in the PolarDB-X console to view the instance that you created.