Physical and logical standby database

Oracle provides two features that support high availability of the database. In this context, availability is the extent to which a database is accessible on demand. The availability of a database is measured by the perception of an end user. A highly available system is accessible to the end users 24/7. A database might become unavailable due to hardware or software problems. The only way to build a highly available system in the face of hardware failure is to have a secondary or an alternate database running on a separate hardware system. A software failure or data corruption can also make the database unavailable. In such cases, a separate system can be used as a failover system such that all the users and applications can transparently use the second system while the primary system is being repaired. In high availability architecture, the main database is called the primary database and the secondary database is called the standby database. The standby...