Principles of Oracle backup and recovery

 

The backup and recovery capabilities are "broken. The principle is briefly introduced here:

 

Oracle records the changes of all data files in the form of logs. Therefore, as long as all ORACLE data files are backed up in a certain period of time and all the logs generated since the backup start time, you can use the backup data file to repeat the change information in the log to restore the data. If there is no data file at a certain time point as the starting point of application change, therefore, Log changes do not have a foothold. Therefore, the goal of backup is to meet this condition.

 

How are data files and log files linked?

 

The data file header contains RBA. With RBA, you can know exactly which logfile (archivelog or online redo) is needed during recovery ), this associates logs with data files.

In addition, there are two familiar figures: Restore and recover

① Restore: overwrite the file back.

② RECOVER: Apply logs based on the files that are overwritten