Limitations of ApsaraDB RDS for MySQL-ApsaraDB RDS(RDS)-阿里云帮助中心

Docs ICP Filing Console

This topic describes the limitations of ApsaraDB RDS for MySQL, which ensure the stability and security of your instances.

Note

In this topic, limitations apply to all versions unless otherwise specified.

For information about the limitations of other database engines, see the following topics:

Specification and performance limits

Resource	Specification	Description
Storage capacity	premium local SSD: up to 8,000 GB standard SSD: up to 6,000 GB ESSD: up to 64,000 GB	The maximum storage capacity varies by instance type. For more information, see Primary ApsaraDB RDS instance types.
Temporary table space	premium local SSD: up to 300 GB cloud disk: unlimited	The maximum temporary table space for an instance that uses a premium local SSD is 300 GB. Exceeding this limit may cause frequent high-availability switchovers and downtime.
Connections	Up to 100,000	The maximum number of connections varies by instance type. For more information, see Primary ApsaraDB RDS instance types.
IOPS	premium local SSD: up to 144,000 cloud disk: see IOPS	None
Memory size	premium local SSD: up to 720 GB cloud disk: up to 768 GB	On ApsaraDB RDS for MySQL instances that use cloud disks, the operating system and management services consume some memory, so the actual available memory is less than the specified size. Memory consumption details: Underlying operating system: about 500 MB to 700 MB. RDS-related management services: about 500 MB.
JSON field	A JSON field can store a maximum of 4 GB of data.	None

Quotas

Quota	Limit
Read-only instances	You can create a maximum of 10 read-only instances for each primary instance.
Primary instances	You can have a maximum of 200 pay-as-you-go or serverless primary instances. You can request a quota increase in Quota Center.
Tags	Each tag key must be unique. You can add a maximum of 20 tags to an instance. You can tag up to 50 instances at a time. For more information, see Create tags.
Free backup storage quota	For instances that use premium local SSDs: 50% of the purchased storage capacity. For instances that use cloud disks: 200% of the purchased storage capacity. Excess backup storage (GB) = Data backup size + Log backup size - Free quota. The result is rounded up to the nearest integer. For more information about backups, see Backup fees.
Backup retention period	The default backup retention period is 7 days, and the maximum is 730 days. Backups retained for more than 730 days are converted to archived backups, which incur lower storage fees. For more information, see Backup fees.
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

Item	Description
Instance name	Must be 2 to 255 characters long. Can contain uppercase or lowercase letters, Chinese characters, digits, underscores (_), and hyphens (-). Must start with a letter or a Chinese character.
Username	The username must be 2 to 32 characters long for MySQL 8.4, 8.0, or 5.7, or 2 to 16 characters long 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 within the instance. Cannot be an SQL keyword.
Database name	Must be 64 characters or less. 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 within the instance. Cannot be an SQL keyword.
User-defined function (UDF) name	Avoid using reserved keywords.

Security limits

Item	Description
Password	Passwords must meet the following requirements: Must be 8 to 32 characters long. Must 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 change the port number. For more information, see View or change the endpoints and ports of an ApsaraDB RDS for MySQL instance.
Cloud disk encryption	You can enable cloud disk encryption only when you create an instance. After it is enabled, you cannot disable it.
Security groups	An instance can belong to a maximum of 10 security groups. If an ApsaraDB RDS instance and an ECS instance are in different security groups, the ECS instance cannot access the ApsaraDB RDS instance. An ApsaraDB RDS instance can be added only to security groups of the same network type. For example, if the instance is in a VPC, it can be added only to VPC security groups. If the instance is in the classic network, it can be added only to classic network security groups. For more information, see Configure a security group.
IP address whitelist	An instance can have up to 50 whitelist groups, and each group can contain up to 1,000 IP addresses or CIDR blocks. For more information, see Configure an IP address whitelist for an ApsaraDB RDS for MySQL instance.
Account permissions	ApsaraDB RDS does not provide root or superuser (sa) permissions. The XA_RECOVER_ADMIN permission has the following limits: This permission is supported only by ApsaraDB RDS for MySQL instances that run MySQL 8.0 or 8.4. You must manually grant this permission by using the `GRANT` command to accounts that you create in the ApsaraDB RDS console. Accounts created by other means, such as by using the `CREATE USER` command in a client, cannot be granted this permission.
Privileged accounts	You can create and manage privileged accounts only in the console or by calling an API. A privileged account can terminate any connection. Each instance can have only one privileged account.
Standard accounts	You can create and manage standard accounts in the console, by calling an API, or by running SQL statements. You cannot use a standard account to create or manage other accounts, or to terminate connections established by other accounts. By default, a standard account only has permission to connect to the current database. You must grant the permissions on a specific database to the standard account in the console. Alternatively, you can run the GRANT statement to grant the required permissions to the standard account.
Instance parameters	Most instance parameters can be modified in the console or by calling an API. For security and stability reasons, some parameters cannot be modified.

Operational limits

Item	Description
Backup and recovery	Backup limits: You can perform logical backups by using a command-line tool or a GUI tool. You can perform physical backups only in the console or by calling an API. Recovery limits: You can restore logical data by using a command-line tool or a GUI tool. You can perform physical recovery only in the console or by calling an API.
MySQL storage engine	Only the InnoDB storage engine is supported. X-Engine is no longer available for new purchases. We recommend that you convert existing X-Engine instances to the InnoDB engine and enable storage compression to reduce storage costs. ApsaraDB RDS for MySQL no longer supports the TokuDB storage engine as of August 1, 2019. This is because Percona has discontinued support for TokuDB, leaving many known bugs unfixed, which can cause business losses in extreme cases. For information about how to change the storage engine, see [Discontinued] Convert the TokuDB engine to the InnoDB engine. The MyISAM storage engine is not supported. Due to its inherent defects that may cause data loss, MyISAM tables in an instance are automatically converted to InnoDB tables. For more information, see Why is the MyISAM storage engine not supported by ApsaraDB RDS for MySQL? The Memory storage engine is not supported. Tables that use the Memory engine are automatically converted to InnoDB tables.
Logs	Logging is enabled by default for ApsaraDB RDS for MySQL and cannot be disabled. For ApsaraDB RDS for MySQL, the binlog_format parameter is fixed to ROW and cannot be changed.
Primary-secondary replication	ApsaraDB RDS for MySQL provides a primary-secondary replication architecture (except for RDS Basic Edition). The secondary instance of an RDS High-availability Edition instance is not readable. The secondary nodes of an RDS Cluster Edition instance are readable.
Instance restart	You must restart an instance in the console or by calling an API.
Network settings	If a MySQL 5.5 or MySQL 5.6 instance resides in the classic network and has database proxy enabled, you cannot enable net.ipv4.tcp_timestamps in SNAT mode.
Storage space	If an instance's storage space is full, it is automatically locked and becomes unusable. We recommend that you regularly check your storage usage. For information about the causes of and solutions for instance locks, see Causes of and solutions for high storage usage of an ApsaraDB RDS for MySQL instance.
Size of a single table	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 structure and support querying built-in help information by using the HELP command. However, this table may be empty in some versions, causing the command to return no results. If this occurs, you can manually import a script to populate the help data.
Public endpoint	You must manually apply for a public endpoint.
Instance restart	You must restart an instance in the console or by calling an API.
GTID	Global Transaction Identifier (GTID) is enabled by default on ApsaraDB RDS for MySQL instances and cannot be disabled.

Previous：Billing FAQNext：Announcements and updates

该文章对您有帮助吗？