Constraints

The following tables list the constraints designed to ensure the stability and security of FlexusRDS instances.

Specifications

**Table 1** Specifications
Item	Constraints	Description
Storage space	The purchased storage space depends on the selected instance class.	You can enable storage autoscaling for your instance after the instance is created. Storage can autoscale to no more than 4 TB.

Quotas

**Table 2** Quotas
Item	Constraints	Description
Tags	A maximum of 20 tags can be added for a DB instance.	For more information, see Managing Tags.
Free backup space	FlexusRDS provides free backup space of the same size as your purchased storage space.	After you pay for the storage space of your instance, you will get a backup space of the same size for free. For more information, see How Is FlexusRDS Backup Data Billed?
Retention period of automated backups	The default value is seven days and cannot be changed.	7-day retention can meet your requirements in most cases. If you want to retain backups for more than seven days, create manual backups.
Log retention period	Error log details: 30 days Slow query log details: 7 days	For more information, see Logs.

Naming

**Table 3** Naming
Item	Constraints
Instance name	4 to 64 characters long Must start with a letter. Only letters (case sensitive), digits, hyphens (-), underscores (_), and periods (.) are allowed.
Backup name	Must be 4 to 64 characters long. Must start with a letter. Only letters (case sensitive), digits, hyphens (-), and underscores (_) are allowed.

Security

**Table 4** Security
Item	Constraints
root permissions	Only the administrator account root is provided on the instance creation page. For details about the supported permissions, see root Permissions. NOTE: Running revoke, drop user, or rename user on root may cause service interruption. Exercise caution when running any of these statements.
root password	8 to 32 characters long Must contain at least three types of the following characters: uppercase letters, lowercase letters, digits, and special characters (~ ! @ # $ % ^ * - _ = + ? , ( ) & . \| ). For more information, see Resetting the Administrator Password.
Database port	3306
System account	To provide O&M services, the system automatically creates system accounts when you create FlexusRDS instances. These system accounts are unavailable to you. rdsAdmin: a management account with the highest permission. It is used to query and modify instance information, rectify faults, migrate data, and restore data. rdsRepl: a replication account, used to synchronize data from the primary instance to the standby instance. rdsBackup: a backup account, used for backend backup. rdsMetric: a metric monitoring account used by watchdog to collect database status data.

Instance Operations

**Table 5** Instance operations
Item	Description
Storage engine	Only the InnoDB storage engine is supported.
Instance deployment	Cloud servers where DB instances are deployed are not directly visible to you. You can only access the DB instances through IP addresses and database ports.
Data migration	Data Replication Service (DRS) can be used to migrate data. It is easy to use and can complete a migration task in minutes. DRS facilitates data transfer between databases, helping you reduce DBA labor costs and hardware costs.
Primary/Standby replication	FlexusRDS uses a primary/standby dual-node replication cluster. You do not need to set up replication additionally. The standby instance is not visible to you and therefore you cannot access it directly.
Rebooting a DB instance	FlexusRDS instances cannot be rebooted through commands. They must be rebooted on the management console.
Viewing backups	You can download automated and manual backups for local storage. To download a backup, you can use OBS Browser+, the current browser, or the download URL. For more information, see Downloading a Full Backup.
Log management	Logging is enabled by default and cannot be disabled. Binary logging is enabled by default.

root Permissions

**Table 6** root permissions
Permission	Level	Description	Supported
Select	Table	Query permissions	Yes
Insert	Table	Insert permissions
Update	Table	Update permissions
Delete	Table	Delete permissions
Create	Database, table, or index	Permissions of creating databases, tables, or indexes
Drop	Database or table	Permissions of deleting databases or tables
Reload	Server management	Permissions of running the following commands: flush-hosts, flush-logs, flush-privileges, flush-status, flush-tables, flush-threads, refresh, and reload
Process	Server management	Permissions of viewing processes
Grant	Database, table, or stored program	Permissions of granting access control
References	Database or table	Foreign key operation permissions
Index	Table	Index permissions
Alter	Table	Permissions of altering tables, such as adding fields or indexes
Show_db	Server management	Permissions of viewing database connections
Create_tmp_table	Server management	Permissions of creating temporary tables
Lock_tables	Server management	Permissions of locking tables
Execute	Stored procedure	Permissions of executing storage procedures
Repl_slave	Server management	Replication permissions
Repl_client	Server management	Replication permissions
Create_view	View	Permissions of creating views
Show_view	View	Permissions of viewing views
Create_routine	Stored procedure	Permissions of creating storage procedures
Alter_routine	Stored procedure	Permissions of altering storage procedures
Create_user	Server management	Permissions of creating users
Event	Database	Event triggers
Trigger	Database	Triggers
Super	Server management	Permissions of killing threads	No NOTE: For more information, see Why Does the Root User Not Have the Super Permission?
File	File on the server	Permissions of accessing files on database server nodes	No
Shutdown	Server management	Permissions of shutting down databases
Create_tablespace	Server management	Permissions of creating tablespaces