This topic describes the relationships between log streams, partitions, and replicas.
A log stream is a group of log data that increments consecutively. Log streams record all change operations in the database. Changes are the basis for the synchronization of all data. The replicas, primary and standby databases, and backup data all depend on the change information recorded in logs.
OceanBase Database V4.x aggregates physical change records into several well-organized log streams, including one system log stream and multiple user log streams. All physical changes made in the system are recorded in log streams. Fault recovery, log archiving, and standby database synchronization are all based on the same set of physical change information.
Within a tenant, a log stream can have multiple replicas that synchronize data with each other by using the Paxos protocol. A recovery point objective (RPO) of 0 and a recovery time objective (RTO) of less than 8s can be achieved when the minority of replicas fail.
In OceanBase Database V4.x, partitions are a logical concept for users. It is a mechanism used to divide and manage table data.