This topic introduces the limitations on the physical standby database solution.
| Limitation | Description |
|---|---|
| Maximum number of standby tenants supported by one primary tenant | Unlimited |
| Requirement for the primary and standby tenants to have homogeneous resources | Not required. It is recommended for the primary and standby tenants to use the same resource specifications. |
| Parameters | Parameters of the primary and standby tenants are independent and not physically synchronized. If a parameter of the primary tenant is modified, it needs to be evaluated whether the same parameter of the standby tenant needs to modified as well. |
| System variables | System variables of the primary and standby tenants are physically synchronized. If a system variable of the primary tenant is modified, the system will synchronize the same system variable on the standby tenants. |
| Users and user passwords | Creating users and changing user passwords are only supported on the primary tenant. The updated information will be synchronized to the standby tenants. |
| Read/write operations | Read operations are supported on the standby tenants, while write operations are not supported. |
| Minor and major compactions | Minor compactions of the primary and standby tenants are independent. Major compactions are not performed on the standby tenants. Instead, the major compaction information is synchronized from the primary tenant to the standby tenants. |
| Switchover | All replicas of the log streams on the standby tenants must be online. |
| Failover | All replicas of the log streams on the standby tenants must be online. |