A user tenant corresponds to a database instance in a conventional database management system. It is created by the system tenant according to business needs. A user tenant has all the characteristics of a database instance. The main ones include:
- It can create its own users.
- It can create databases (only supported in MySQL-compatible mode), tables, and other database objects.
- It has its own system tables and system views.
- It has its own system variables.
- Other characteristics that a database instance typically has.
The metadata of all user data is stored within the user tenant, so each tenant has its own namespace and is inaccessible from each other. The system tenant manages all user tenants, and the hierarchical relationship between the system tenant and user tenants is illustrated in the diagram below.
Users created in a user tenant can only log in to that specific tenant and remain invisible to other tenants.
- For a MySQL-compatible tenant, user information can be queried from the
mysql.userview. - For an Oracle-compatible tenant, user information can be queried from the
ALL_USERSview.
Tables created in a user tenant are invisible to other tenants.
- For a MySQL-compatible tenant, information about all user tables in the tenant can be queried from the
information_schema.tablesview. - For an Oracle-compatible tenant, information about all user tables in the tenant can be queried from the
ALL_TABLESview.
A user tenant is only able to modify system variables within its own tenant.
- For a MySQL-compatible tenant, information about system variables can be queried from the views
information_schema.global_variablesandinformation_schema.session_variables. It can also be queried using theSHOW VARIABLESstatement. - For an Oracle-compatible tenant, the
SHOW VARIABLESstatement can be used to query all system variables within the tenant.