Limits of ApsaraDB RDS for MySQL - ApsaraDB RDS - Alibaba Cloud Documentation Center

This topic describes the limits of ApsaraDB RDS for MySQL. Before you use ApsaraDB RDS for MySQL, we recommend that you take note of these limits to ensure the stability and security of your database system.

Note

In this topic, if no specific MySQL versions are mentioned, the limits that correspond are imposed regardless of the MySQL versions.

For more information about the limits of ApsaraDB RDS that is used together with a different database engine, see the following topics:

Limits on specifications and performance

Item	Specification	Description
Storage capacity	RDS instances that use local SSDs: up to 6,000 GB. RDS instances that use standard SSDs: up to 6,000 GB. RDS instances that use enhanced SSDs (ESSDs): up to 64,000 GB.	The maximum storage capacity of an RDS instance varies based on the instance type. For more information, see Primary ApsaraDB RDS instance types.
Temporary table size	RDS instances that use local disks: up to 300 GB. RDS instances that use standard cloud disks: unlimited.	The maximum size of temporary tables in an RDS instance that uses local disks is 300 GB. If the size of temporary tables exceeds 300 GB, the RDS instance may encounter frequent high-availability switchovers and downtime issues.
Connections	Up to 100,000.	The maximum number of connections to an RDS instance varies based on the instance type. For more information, see Primary ApsaraDB RDS instance types.
IOPS	RDS instances that use local disks: up to 144,000. RDS instances that use cloud disks: For more information, see IOPS.	None.
Memory capacity	RDS instances that use local disks: up to 720 GB. RDS instances that use cloud disks: up to 768 GB.	For RDS instances that use cloud disks, the memory includes the memory that is occupied by the RDS-related management services and the underlying operating system. Therefore, the available memory of an RDS instance may be less than the memory capacity that is supported by the instance type. The following list provides the amount of memory that is occupied by different components: The underlying operating system occupies 500 MB to 700 MB of memory. The RDS-related management services occupy approximately 500 MB of memory.
JSON field size	A JSON field can store up to 4 GB of data.	N/A

Limits on quotas

Item	Description
Read-only RDS instances	Up to 10 read-only RDS instances can be created and attached to the primary RDS instance. For more information about read-only RDS instances, see Overview of read-only ApsaraDB RDS for MySQL instances.
Primary RDS instances	Up to 200 pay-as-you-go or serverless primary RDS instances can be created within each Alibaba Cloud account. You can go to the Quota Center page to apply for a quota increase for your Alibaba Cloud account.
Tags	The key of a tag must be unique. You can add up to 20 tags to an RDS instance. You can add tags to up to 50 RDS instances at a time. For more information, see Add tags to ApsaraDB RDS instances.
Free quotas on backup storage	RDS instances that use local disks: Free quota on backup storage = 50% × Purchased storage capacity RDS instances that use cloud disks: Free quota on backup storage = 200% × Purchased storage capacity If your backup storage exceeds the free quota, you are charged for the excess backup storage that you use. You can calculate your excess backup storage by using the following formula: Excess backup storage = Size of data backup files + Size of log backup files - Free quota. Unit: GB. You can round the obtained result only up to the next integer. For more information, see Backup storage fees.
Backup retention period	The default retention period is 7 days, and the maximum retention period is 730 days. Data backup files that are retained for more than 730 days are archived. You are charged less for archived backup files than for regular backup files. For more information, see Backup storage fees.
Log retention period	Error logs are retained for 30 days. The details about slow query logs are retained for 7 days. The summary of slow query logs is retained for 7 days. Primary/secondary switchover logs are retained for 30 days. For more information, see View error logs and slow logs.

Limits on names

Item	Description
Instance names	The name of an RDS instance must be 2 to 255 characters in length. The name of an RDS instance can contain letters, digits, underscores (_), and hyphens (-). The name of an RDS instance must start with a letter.
Usernames	For RDS instances that run MySQL 8.0 or MySQL 5.7, the username of an account must be 2 to 32 characters in length. For RDS instances that run MySQL 5.6, the username of an account must be 2 to 16 characters in length. The username of an account can contain lowercase letters, digits, and underscores (_). The username of an account must start with a lowercase letter and end with a lowercase letter or a digit. The username of an account must be unique. The username of an account cannot contain SQL keywords. For more information, see SQL keywords.
Database names	The name of a database can contain up to 64 characters in length. The name of a database can contain lowercase letters, digits, underscores (_), and hyphens (-). The name of a database must start with a lowercase letter and end with a lowercase letter or a digit. The name of a database must be unique. The username of an account cannot contain SQL keywords. For more information, see SQL keywords.
User-defined function (UDF) names	Do not use the reserved keywords in the name of a UDF. For more information, see Reserved keywords of an ApsaraDB RDS for MySQL instance.

Limits on security

Item	Description
Passwords	The password of an account must meet the following requirements: It must be 8 to 32 characters in length. It must contain at least three types of the following characters: uppercase letters, lowercase letters, digits, and special characters. It can contain the following special characters: `! @ # $ % ^ & * () _ + - =`
Ports	By default, an RDS instance is connected over port 3306. You can change the port number based on your business requirements. For more information, see View and manage instance endpoints and ports.
Cloud disk encryption	You can enable cloud disk encryption for an RDS instance only when you purchase the instance. Cloud disk encryption cannot be disabled after it is enabled. For more information, see Configure the cloud disk encryption feature.
Security groups	You can configure up to 10 security groups for an RDS instance. After you configure security groups for an RDS instance, the Elastic Compute Service (ECS) instances in the configured security groups can communicate with the RDS instance. The security groups that you configured for an RDS instance must have the same network type as the RDS instance. This means that the network types of the RDS instance and the security groups that you want to configure must both be virtual private cloud (VPC) or classic network. For more information, see Configure a security group for an ApsaraDB RDS for MySQL instance.
IP address whitelists	You can configure up to 50 IP address whitelists for an RDS instance and add up to 1,000 IP addresses and CIDR blocks to an IP address whitelist. For more information, see Configure an IP address whitelist for an ApsaraDB RDS for MySQL instance.
Account permissions	The permissions of the root account or the system administrator account are not provided. The XA_RECOVER_ADMIN permission is subject to the following limits: The permission is supported only for RDS instances that run MySQL 8.0. Only the accounts that you create in the ApsaraDB RDS console have the permission. The accounts that you create by using the CREATE USER statement in the Data Management (DMS) console or on a database client do not have the permission and cannot be granted the permission.
Privileged accounts	You can create and manage privileged accounts in the ApsaraDB RDS console or by using the ApsaraDB RDS API. The privileged account of an RDS instance has permissions to disconnect the database connections that are established by using standard accounts. Only one privileged account can be created for each RDS instance. For more information, see Create an account.
Standard accounts	You can create and manage standard accounts in the ApsaraDB RDS console. You can also use the ApsaraDB RDS API or execute SQL statements to create and manage standard accounts. You cannot use a standard account to create and manage accounts, or disconnect the database connections that are established by using other accounts. By default, a standard account has the permissions only on the database to which the standard account is connected. You must manually grant the permissions on specified databases to each standard account. For more information, see Modify the permissions of a standard account on an ApsaraDB RDS for MySQL instance. You can also execute the GRANT statement to grant the specified permissions to a standard account. For more information, see Account permissions.
Instance parameters	You can modify most of the instance parameters in the ApsaraDB RDS console or by using the ApsaraDB RDS API. For security and stability purposes, some parameters cannot be modified. For more information, see Configure instance parameters.

Limits on operations

Item	Description
Restoration	Limits on backups: You can perform logical backups by using the CLI or the GUI. You can perform physical backups in the ApsaraDB RDS console or by using the ApsaraDB RDS API. Limits on restoration: You can restore data from logical backup files by using the CLI or the GUI. You can restore data from physical backup files in the ApsaraDB RDS console or by using the ApsaraDB RDS API.
Storage engines	Only the InnoDB storage engine and the X-Engine storage engine are supported. For more information about X-Engine, see Introduction to X-Engine. The TokuDB storage engine is not supported. Percona no longer provides support for TokuDB. A large number of known issues in TokuDB cannot be fixed. In extreme cases, these issues may cause business loss. Therefore, ApsaraDB RDS for MySQL no longer supports TokuDB as of August 1, 2019. For more information about how to change the storage engine of an RDS instance, see [EOS/Discontinuation] ApsaraDB RDS for MySQL no longer supports TokuDB. The MyISAM storage engine is not supported due to its inherent defects that may cause data loss. If you create a MyISAM table, ApsaraDB RDS converts the MyISAM table to an InnoDB table. For more information, see Why does ApsaraDB RDS for MySQL not support the MyISAM storage engine? The MEMORY storage engine is not supported. If you create a Memory table, ApsaraDB RDS converts the MEMORY table to an InnoDB table.
Logs	By default, the logging feature is enabled. The logging feature cannot be disabled after it is enabled. The value of the binlog_format parameter is fixed as ROW. This value cannot be changed.
Primary/secondary replication	ApsaraDB RDS for MySQL provides a primary/secondary replication architecture in all RDS editions except for RDS Basic Edition. In RDS High-availability Edition, secondary RDS instances cannot process read requests. In RDS Cluster Edition, secondary nodes can process read requests.
Instance restart	You can restart an RDS instance in the ApsaraDB RDS console or by using 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 feature is enabled for the RDS instance, you cannot enable timestamps in SNAT mode by configuring the net.ipv4.tcp_timestamps parameter.
Storage capacity	If the storage capacity of an RDS instance is exhausted, the RDS instance is automatically locked and cannot provide services. We recommend that you check the storage usage on a regular basis.
Size of a single table	The maximum size of a single table is 16 TB due to the maximum file size that is allowed by the operating system. For more information, see Limits on the size of a single table in ApsaraDB RDS for MySQL.
Help information	You can query detailed help information from the mysql.help_topic table on an RDS instance that runs any MySQL version. The data and schema of the table may vary based on the MySQL version.
Public endpoints	If you want to connect to an RDS instance by using a public endpoint, you must manually apply for a public endpoint. For more information, see Apply for or release a public endpoint for an ApsaraDB RDS for MySQL instance.
Instance restart	You can restart an RDS instance in the ApsaraDB RDS console or by using the ApsaraDB RDS API.