ApsaraDB RDS for MySQL limits - ApsaraDB RDS - Alibaba Cloud Documentation Center

ApsaraDB RDS for MySQL has several limits to ensure the stability and security of instances.

Note

Unless a specific version is mentioned, the limits described in this topic apply to all versions.

For the limits of other database engines, see the following topics:

Specifications and performance limits

Resource	Specification	Description
Storage space	High-performance local disks: up to 8,000 GB Standard SSDs: up to 6,000 GB Enterprise SSDs (ESSDs): up to 64,000 GB	The maximum storage space varies by instance type. For more information, see Primary instance types.
Temporary tablespace size	High-performance local disks: up to 300 GB Cloud disks: unlimited	The maximum temporary tablespace for a high-performance local disk is 300 GB. Exceeding this limit can cause frequent high-availability switches and instance breakdowns.
Connections	Up to 100,000	The maximum number of connections varies by instance type. For more information, see Primary instance types.
IOPS	High-performance local disks: up to 144,000 Cloud disks: see IOPS	None
Memory size	High-performance local disks: up to 720 GB Cloud disks: up to 768 GB	The underlying operating system and ApsaraDB RDS management services of an ApsaraDB RDS for MySQL cloud disk instance consume some memory. Therefore, the actual available memory of the instance is less than the specified memory size. Memory usage details: Underlying operating system: about 500 MB to 700 MB. ApsaraDB RDS management services: about 500 MB.
JSON field	Maximum storable data is 4 GB	None

Quotas

Quota	Limit
Read-only instances	You can create a maximum of 10 read-only instances.
Primary instances	The quota for pay-as-you-go and Serverless primary instances is 200. To increase the quota, submit a request in Quota Center.
Tags	Each tag key must be unique. You can set a maximum of 20 tags. Add tags to a maximum of 50 instances in a batch. To create tags, see Create tags.
Free backup storage quota	Free quota for high-performance local disks: 50% × purchased storage space of the instance. Free quota for cloud disks: 200% × purchased storage space of the instance. The excess usage is calculated as follows: Data backup size + Log backup size - Free quota. The value is measured in GB and rounded up to the nearest integer. For more information about backups, see Backup storage costs.
Instance backup retention period	The default retention period is 7 days. The maximum retention period is 730 days. Data backups retained for more than 730 days are converted to archive backups, which incur lower archive backup fees. For more information, see Backup storage costs.
Log retention period	Error logs: 30 days Slow query log details: 7 days Slow query log statistics: 7 days Primary/secondary switchover logs: 30 days For more information, see View error logs and slow query logs.

Naming limits

Limits	Description
Instance name	Must be 2 to 255 characters in length. Can contain uppercase letters, lowercase letters, Chinese characters, digits, underscores (_), and hyphens (-). Must start with an uppercase letter, a lowercase letter, or a Chinese character.
Account name	Must be 2 to 32 characters in length for MySQL 8.0 or 5.7, and 2 to 16 characters in length for MySQL 5.6. Can contain lowercase letters, digits, and underscores (_). Must start with a lowercase letter and end with a lowercase letter or a digit. Must be unique. Cannot be an SQL keyword.
Database name	Must be up to 64 characters in length. Can contain lowercase letters, digits, underscores (_), and hyphens (-). Must start with a lowercase letter and end with a lowercase letter or a digit. Must be unique. Cannot be an SQL keyword.
User-defined function name	Avoid using reserved keywords.

Security limits

Limitations	Description
Password	The password must meet the following requirements: Be 8 to 32 characters in length. Contain at least three of the following character types: uppercase letters, lowercase letters, digits, and special characters. The special characters are: `!@#$%^&*()_+-=`.
Port	The default port for ApsaraDB RDS for MySQL instances is 3306. You can manually change the port number. For more information, see View or change the internal and public endpoints and ports.
Disk encryption	Disk encryption can be enabled only when you create an instance and cannot be disabled.
Security group	Each instance can be added to a maximum of 10 security groups. If an ApsaraDB RDS instance and an Elastic Compute Service (ECS) instance are in different security groups, the ECS instance cannot access the RDS instance. You can add an RDS instance only to a security group of the same network type. For example, if the instance is in a virtual private cloud (VPC), you can add it only to a VPC-type security group. If the instance is in the classic network, you can add it only to a classic network-type security group. To configure security groups, see Configure a security group.
IP whitelist	Each instance can have up to 50 whitelist groups. Each whitelist group can contain up to 1,000 IP addresses or CIDR blocks. To configure a whitelist, see Configure an IP address whitelist.
Account permissions	ApsaraDB RDS does not provide root or sa permissions. The XA_RECOVER_ADMIN permission has the following constraints: Only ApsaraDB RDS for MySQL 8.0 instances support this permission. For accounts created in the RDS console, you must manually grant this permission using the `GRANT` command. Accounts created by other means, such as using the `CREATE USER` command on a client, do not have this permission and cannot be granted this permission.
Privileged account	A privileged account can be created and managed only in the console or by calling an API. It can be used to disconnect any account. You can create only one privileged account for each instance.
Standard account	Standard accounts can be created and managed in the console, by calling an API, or using SQL statements. Standard accounts cannot be used to create or manage other accounts, or to disconnect other accounts. By default, a standard account only has the permission to connect to the current database. You need to grant permissions on specific databases to the standard account in the console. You can also use a GRANT statement to grant the required permissions.
Instance parameters	Most instance parameters can be modified in the console or by calling an API. For security and stability, some parameters cannot be modified.

Instance operation limits

Limits	Description
Backup and recovery	Backup limits: Perform logical backups using the command line or a graphical user interface (GUI). Perform physical backups only in the console or by calling an API. Recovery limits: Recover logical data using the command line or a GUI. Perform physical recovery only in the console or by calling an API.
MySQL storage engine	Only the InnoDB engine is supported. You can no longer create new instances that use the X-Engine engine. Convert existing X-Engine instances to use the InnoDB engine and enable storage compression to reduce storage costs. The TokuDB engine is not supported. Because Percona no longer supports TokuDB, many known bugs cannot be fixed. In extreme cases, this can cause business interruptions. Therefore, ApsaraDB RDS for MySQL no longer supports the TokuDB engine since August 1, 2019. For information about how to convert the engine, see [Discontinuation] Convert the TokuDB engine to the InnoDB engine. The MyISAM engine is not supported. Due to the inherent defects of the MyISAM engine, data loss may occur. MyISAM tables in an instance are automatically converted to InnoDB tables. For more information, see Why is the MyISAM engine not supported by ApsaraDB RDS for MySQL?. The Memory engine is not supported. Tables that use the Memory engine are automatically converted to use the InnoDB engine.
Logs	Logging is enabled by default for ApsaraDB RDS for MySQL and cannot be disabled. The binlog_format parameter for ApsaraDB RDS for MySQL is fixed to ROW and cannot be modified.
Primary/secondary replication	ApsaraDB RDS for MySQL provides a primary/secondary replication architecture (except for Basic Edition instances). The secondary instance of a high-availability series instance is not readable. The secondary nodes of a Cluster Edition instance are readable.
Instance restart	Restart the instance in the console or by calling an API.
Network settings	If a MySQL 5.5 or MySQL 5.6 instance is in the classic network and has database proxy enabled, do not enable net.ipv4.tcp_timestamps in SNAT mode.
Storage space	If the storage space of an instance is full, the instance is automatically locked. This affects its use. Regularly check the storage usage.
Single table size	Due to operating system file size limits, the maximum size of a single table in ApsaraDB RDS for MySQL is 16 TB.
Help information	All MySQL versions include the `mysql.help_topic` table schema and support querying built-in help information using the HELP command. However, the default data content may vary by version. Some versions may not have the help data initialized, which results in empty query results. You can manually import a script to complete the data and enable the HELP command.
Public endpoint	A public endpoint must be manually requested.
Restart an RDS instance	Restart the instance using the console or by calling an OpenAPI.