If you restore the archived redo log files and data files, then you must perform media recovery before you can open the database. Any database transactions in the archived redo log files not reflected in the data files are applied to the data files, bringing them to a transaction-consistent state before the database is opened.
如果你恢復了歸檔的redo 日誌文件和數據庫文件，之後你必須在打開數據庫之前執行介質恢復（Media Recovery）。一切在歸檔日誌文件裏的沒有寫到數據文件裏的數據庫交易記錄將會被寫入到數據文件中，以使數據庫在打開之前保持數據一致性。
Media recovery requires a control file, data files (typically restored from backup), and online and archived redo log files containing changes since the time the data files were backed up. Media recovery is most often used to recover from media failure, such as the loss of a file or disk, or a user error, such as the deletion of the contents of a table.
介質恢復需要一個控制文件，數據文件（特別是從備份中恢復出來的）和online狀態且歸檔的redo 日誌文件，這個日誌文件得包含自從數據文件備份以來產生的變化。介質恢復經常用來恢復介質失敗，就像是文件和磁盤的丟失或者一個用戶錯誤像是刪除了一個表的內容。
Media recovery can be a complete recovery or a point-in-time recovery. Complete recovery can apply to individual datafiles, tablespaces, or the entire database. Point-in-time recovery applies to the whole database (and also sometimes to individual tablespaces, with automation help from Oracle Recover Manager (RMAN)).
介質恢復可以執行完全恢復和指定某個時間點的恢復（專業術語不是很清楚了），完全恢復可以應用於單個數據文件，表空間或整個數據庫。而時間點恢復應用於整個數據庫（有時也可以使用Oracle Recover Manager（RMAN）的自動化幫助來處理各個表空間）
In a complete recovery, you restore backup data files and apply all changes from the archived and online redo log files to the data files. The database is returned to its state at the time of failure and can be opened with no loss of data.
在完全恢復中，你要恢復備份的數據文件和將所有的歸檔日誌和redo日誌的變化應用到數據文件中。數據庫會恢復到它失敗時的那個狀態，打開數據庫時，不會有數據損失。
In a point-in-time recovery, you return a database to its contents at a user-selected time in the past. You restore a backup of data files created before the target time and a complete set of archived redo log files from backup creation through the target time. Recovery applies changes between the backup time and the target time to the data files. All changes after the target time are discarded.
在時間點恢復中，你將數據庫的狀態返回到用戶選擇的那個時間點。你從一個備份中恢復數據文件，這個數據文件是在你選擇的時間點（目標時間）之前，而且必須有從之前的數據文件備份開始的完整的歸檔的redo日誌文件。恢復將會應用數據文件從備份時間到目標時間的的所有改變。而在目標時間後的所有改變將會拋棄。
RMAN enables you to perform both a complete and a point-in-time recovery of your database. However, this documentation focuses on complete recovery.
RMAN允許你去執行完全恢復和基於時間點的恢復。
