21 User-Managed Incomplete Recovery.pptVIP

User-Managed Incomplete Recovery Incomplete Recovery Overview Situations RequiringIncomplete Recovery Complete recovery fails because an archived log is lost. All unarchived redo log files and a datafile are lost. User error An important table was dropped. Invalid data was committed in a table. Current control file is lost and a backup control file must be used to open the database. Types of Incomplete Recovery There are three types of incomplete recovery: Time-based recovery Cancel-based recovery Change-based recovery You may need to recover using a restored control file when: Control files are lost Performing incomplete recovery to a point when the database structure is different than the current Incomplete Recovery Guidelines Follow all steps carefully. Take whole database backups before and after recovery. Always verify that the recovery was successful. Back up and remove archived logs. Incomplete Recovery and the Alert Log Check the alert log before and after recovery Contains error information, hints, and SCNs User-Managed Procedures for Incomplete Recovery Shut down and back up the database. Restore all datafiles. Do not restore the control file, redo logs, password file, or parameter file. Mount the database. Recover the datafiles to a point before the time of failure. Open the database with RESETLOGS. check recovery is successful!! 6. Perform a closed database backup. RECOVER Command Overview Recover a database until cancel: Recover a database until time:  Recover using backup control file: Time-Based Recovery: Example Scenario: The current time is 12:00 p.m. on March 9, 2002. The EMPLOYEES table has been dropped. The table was dropped at approximately 11:45 a.m. Database activity is minimal because most staff are currently in a meeting. The table must be recovered. UNTIL TIME Recovery Cancel-Based Recovery: Example Scenario: The current time is 12:00 p.m. on March 9,2002. The EMPLOYEES table was dropped while someone was trying to fix bad bloc