This topic describes the limits of ApsaraDB RDS for MySQL. Before you use ApsaraDB RDS for MySQL, we recommend that you understand these limits. This allows you to ensure the stability and security of your RDS instance.
For more information about the limits of other database engines, see the following topics:
- Limits of ApsaraDB RDS for SQL Server
- Limits of ApsaraDB RDS for PostgreSQL
- Limits of ApsaraDB RDS for PPAS
- Limits of ApsaraDB RDS for MariaDB
The following table provides details about these limits.
|Instance parameters||You can reconfigure most of the instance parameters by using the ApsaraDB RDS console or the ApsaraDB RDS API. However, for security and stability purposes, some parameters cannot be reconfigured. For more information, see Use the console to set parameters.|
|Root permissions||The permissions of the root user and system administrator are not provided.|
|Storage engine||Only the InnoDB and X-Engine storage engines are supported. For more information about X-Engine, see X-Engine overview.
|Replication||ApsaraDB RDS for MySQL provides a primary/secondary replication architecture. The secondary RDS instance in this architecture is hidden and cannot be connected to your application. This architecture is not supported in the Basic Edition.|
|Instance restart||You can restart an RDS instance only by using the ApsaraDB RDS console or the ApsaraDB RDS API.|
|Network settings||If an RDS instance runs MySQL 5.5 or MySQL 5.6 in the classic network and the database proxy of the instance is enabled, you cannot enable net.ipv4.tcp_timestamps in SNAT mode.|
If the storage usage of an RDS instance is abnormally high, ApsaraDB RDS locks the instance. This prevents data loss that may be caused by accidental operations. You can unlock the instance by upgrading the specifications of the instance.
|Help information||If you are using MySQL 8.0, you can query detailed help information from the mysql.help_topic table. If you are not using MySQL 8.0, the mysql.help_topic table is empty.|
|Number of instances||The number of pay-as-you-go RDS instances that you can create is limited to 30. You can go to the Quota Center console to increase the limit.|