Oracle Database restoration method (1)

Oracle DatabaseOracle is a relational database management system of oracle, and oracle database is a large database system. oracle databases are commonly used. When we use an oracle database, we always hope that the database content is reliable and correct, but the operations of the oracle database system are affected by computer system faults (hardware faults, software faults, network faults, process faults and system faults, it affects the correctness of data in the oracle database, and even damages the oracle database, so that all or part of the data in the oracle database is lost. How can we avoid these damages? The answer is as follows.

Therefore, when the above fault occurs, we hope to reconstruct the complete database, which is called Oracle database recovery. The recovery process can be roughly divided into the recovery (Restore) and recovery (Restore) processes. Oracle Database recovery can be divided into the following two types:

Instance fault consistency recovery

When an instance fails unexpectedly (such as power failure or background process failure) or unexpectedly (issue a shutdoum abort statement), The instance must be restored. The instance restores the Oracle database to the transaction consistency state before the fault. If an instance fault is found in the online backup, the media must be restored. In other cases, Oracle automatically performs instance recovery when the next database is started (new instances are assembled and opened. If needed, the instance is automatically restarted from the assembly status to the open status, which is handled:

1. Roll Forward to learn about the data not recorded in the recovery data file. This data is recorded in online logs, including restoring the content of the rollback segment.

2. Roll Back uncommitted transactions and regenerate the operation specified by the rollback segment in step 1.

3. Release the resources that are being processed by the firm at the time of the fault.

4. resolves any outstanding distributed transactions that are being committed in a phase at the time of failure.