This topic describes the limitations on the Physical Standby Database solution.
| Item | Description |
|---|---|
| Maximum number of standby tenants supported by one primary tenant | Unlimited |
| Whether homogeneous resources are required for the primary and standby tenants | Homogeneous resources are not required. We recommend that you use the same resource specifications for the primary and standby tenants. |
| System parameters | The parameters of the primary tenant are independent of those of a standby tenant, and parameter modifications are not physically synchronized. After you modify a parameter of the primary tenant, you must assess whether to modify the corresponding parameter of the standby tenants. |
| System variables | System variables of the primary and standby tenants are physically synchronized. If you modify a system variable of the primary tenant, the system synchronously modifies the corresponding system variable of the standby tenants. |
| User and user password | You can create users and change user passwords only in the primary tenant. The updated information is synchronized to the standby tenants. |
| Read/write operations | A standby tenant supports only read operations. |
| Minor and major compactions | Minor compactions in the primary tenant are independent of those in the standby tenants. Major compactions are not performed in a standby tenant. Instead, the major compaction information is synchronized from the primary tenant to the standby tenants. |
| Switchover | All replicas of log streams of the standby tenant must be online. |
| Failover | All replicas of log streams of the standby tenant must be online. |