Creating Read-Only Instance

Last updated: 2021-08-02 18:40:09

    This document describes how to create a read-only instance in the TDSQL-C console.


    TDSQL-C allows you to create one or more read-only instances in a cluster, which are suitable for read/write separation and one-write-multiple-read application scenarios and capable of greatly enhancing the read load capacity of your database cluster.

    • A TDSQL-C cluster supports two instance types: primary instance (read-write instance) and secondary instance (read-only instance).
    • A TDSQL-C cluster provides read-write and read-only addresses by default. You can access all read-only instances at the cluster's read-only address. After a read-only instance is created, new read-only connection requests to the read-only address will be automatically forwarded to the read-only instance.
    • A read-only instance is billed in the same way as the read-write instance. For more information, please see Pricing.
    • Unified read/write separation addresses (i.e., read and write requests are separated automatically) are not supported currently.

    For more information on how to access a TDSQL-C cluster, please see Connecting to TDSQL-C Cluster.


    • Read-only and read-write instances share the same storage, so there is no need to maintain the account and database.
    • A read-only instance does not need to be synced with the read-write instance through binlog or does not need to replicate/migrate data. It can be created in seconds.
    • The delay between a read-only instance and the read-write instance is usually within milliseconds, which can be viewed through the read-only instance delay monitoring metric on the instance monitoring page.
    • The specification of a read-only instance can be different from that of the read-write instance, which makes it easier for you to adjust the configuration according to the load. We recommend you keep the specifications of read-only instances the same.


    1. Log in to the TDSQL-C console and click a cluster name or Manage in the Operation column in the cluster list to enter the cluster details page.
    2. In the instance list, click Create to enter the read-only instance purchase page.
    3. Select the desired read-only instance configuration on the purchase page. After confirming that everything is correct, click Buy Now.