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Creating Read-Only Instance

Last updated: 2022-06-07 18:28:14

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


    TDSQL-C for MySQL 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 for MySQL cluster supports two instance types: primary instance (read-write instance) and secondary instance (read-only instance).
    • A TDSQL-C for MySQL 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, 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 for MySQL cluster, see Connecting to TDSQL-C for MySQL 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 copy/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.
    • When you add a monthly subscribed read-only instance in a monthly subscribed cluster, the instance will expire at the same time as the cluster.


    1. Log in to the TDSQL-C for MySQL console and click a cluster ID in the cluster list or Manage in the Operation column to enter the cluster management page.
    2. On the cluster management page, select the Instance List tab and click Create to enter the read-only instance purchase page.
    3. On the purchase page, select the target read-only instance configuration, confirm that everything is correct, and click Buy Now.
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