Oracle Backup and Recovery

A backup is a copy of data from your database that can be used to reconstruct that data.  There are two types of Backup:

Logical Backup

  • The logical backup technique uses the IMPORT/EXPORT utilities to create the
    backup copy of the database.
  • Logical backup means backing up the individual database objects such as tables, schemas, views, indexes using the utility called EXPORT, provided by the Oracle. 
  • A logical backup can be used to recover the contents of the database to the last backup.

Physical Backup

  • Physical backups are backups of the physical files: such as datafiles, control files, and archived redo logs.
  • Redo logs file contains all your transaction in binary format. 
  • The following SQL query is used to view redo log files:
           SELECT * FROM V$LOG;
  • This type of backup is often used to recover the database to the point of failure.
  • Physical backup has two types:
    • Online Backup and 
    • Offline backup
  • Online Backup (Consistent backup OR Hot backup)
    • Pros: Pointing time recovery and no database shutdown
    • Cons: Additional IO resources needed
  • Offline Backup (Inconsistent backup OR Cold backup)
    • Pros: Consistent and easy to manage
    • Cons: No pointing time recovery and unavailability to end users

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