It gives information such as number of full table scans occurred, cost, and usage of indexes.Īnswer. It is a utility provided that gives the statistics about the performance of the query. How do you retrieve a dropped table in 10g?Īnswer. There are two modes in which the hot backup works. In such cases, hot backup approach should be used. Hot backup: A few systems that need to support continuous operation, it is difficult to bring down the database without interrupting the service provided to the users. Therefore, in these situations physical backups should be preferred. However, unlike physical back, it should not be used to create an OS back up copy because restoring using this approach would make it possible to correct the damaged data files. A logical backup can be used to restore the database to the last backup. A logical backup backs-up the contents of the database. Logical Backup: In logical backup technique, the IMPORT/EXPORT utilities are used to create the backup of the database. This is useful to restore the system to an earlier point whenever needed. Physical Backup: The operating system saves the database files onto tape or some other media. Once the backup has been completed the DBA can restart the database. What are different types of backup? What are Hot, Cold, logical, Physical backups?Ĭold Backup: In this type of backup, after the database is shut down, DBA exits the SVRMGR utility and copies the log files, data files and control files onto a backup media. In such cases, Oracle breaks the deadlock by forcing one or more transactions to rollback. When a deadlock occurs, the transactions fail to go ahead – they are stuck. When two or more users are waiting for access to data that has been locked by each other, it is known as deadlock.
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