OceanBase Database supports the multi-tenancy architecture. However, not all the memory configured for an OceanBase database can be allocated to tenants, because tenants share specific resources and features on each OBServer node. As the memory occupied by the shared resources and features does not belong to any user tenant, this type of memory is managed as the internal system memory.
You can set the system_memory parameter to specify the upper limit of the internal system memory. This parameter is an estimate for the memory internally used by the system, and it limits the maximum memory that can be used by tenants, which is calculated by subtracting system_memory from memory_limit.
Assume that the maximum memory size for an OceanBase database is 80 GB and system_memory is 20 GB, the memory that can be assigned to tenants is 60 GB.