Overview

After the read-only instance is enabled, you can create a Proxy Instance, set and manage the read traffic weights of master instances and read-only instances, and set the master instance with Fexible read capability expansion function, so as to improve the throughput of users and reduce the pressure of the master instance when there are many read requests.

You can also enable the read traffic bearing function of the read-only instance in your own business codes, and assign the read traffic to specified read-only instance.

Instance relation

The relationship among master instance, read-only instance and proxy instance is as shown in the following figure. You can create a read-only instance and an proxy instance for the master instance on the details page of the master instance after creating the master instance.

• Master instance: bear the reading and writing requests;
• Read-only instance: bear the reading requests;
• Proxy instance: set and manage the read traffic weight ratio of the master instance and the read-only instance.

Billing standard

• Billing item: keep it consistent with the billing items under the master instance.
• Billing method: postpaid is supported, but prepaid is not support for the moment.
• Billing details: refer to Proxy Instance Price.

Proxy instance price

• Regions and available zones: in the same regions as the master instance, the available zone can be different.
• Specification: five specifications of proxy instances are provided, please choose depending on your demand.

Precautions

• Instance version: currently the proxy instance supports the creation of master instances of MySQL 5.6 and MySQL 5.7.
• Quantity restrictions: only one proxy instance can be purchased at a time, and only one proxy instance can be purchased for one master instance.
• Binding relationship: the proxy instance is not allowed to exist alone. Before it is created, a master instance must be created first; when the master instance is released, the corresponding proxy instance will be released along with the master instance.
• Functional restrictions: the proxy instance does not support backup settings and manual backups.
• Master-slave delay strong consistent reading strategy; in the same session, after the execution of write SQL, the read SQL will be executed immediately, and the read SQL will be sent to the main library within the time interval of write_time_interval. The write_time_interval is 200ms by default. Modification of this parameter is not supported now.
• Business has high requirements for strong consistent reading, so it is recommended to open the transaction. If a transaction is opened, SQL will be sent to the main library.