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ORA-1578: ORACLE data block corrupted
Issue: Database is in Flashback Mode. Enabled No logging on some db Tables Recover the database. Truncate those no logging Temporary tables. Now we get error message ORA-1578: ORACLE data block corrupted Reason: Oracle says it is a behavior in 10g and fixed in 11g Rel1. Cannot Reuse a Corrupt Block in Flashback Mode, ORA-1578 [...]
Flashback Database disabled automatically
Issue 1: Intially Flashback Database was enabled but noticed Flashback was disabled automatically long time ago. Reason: It could be because the flashback area 100% Once Flashback Area become 100% full then oracle will log in Alert that Flashback will be disabled and it will automatically turn off Flash Back without user intervention.
How can I check if there is anything rolling back?
It depends on how you killed the process. If you did and alter system kill session you should be able to look at the used_ublk block in v$transaciton to get an estimate for the rollback being done. If you killed to server process in the OS and pmon is recovering the transaction you can look [...]
Explain the relationship among database, tablespace, and datafile.
The database is logically divided into one or more tablespaces. For each tablespace we explicitly create one or more datafiles.
How to recover if we delete a data file at OS level no backup for that?
bring the database to the mount state sql>alter database create datafile ; sql>recover datafile ; sql>alter database open;
How do you see how many instances are running?
In Linux, Unix the command: ps -ef|grep pmon In Windows: services.msc
You lost some datafiles and you don’t have any full backup and the database was running in NOARCHIVELOG mode. What you can do now?
You have lost datafiles and you dont have backup and database is not running in archive log mode…… So we need to recreate the datafiles which will be empty….. you can not recover, becuase you dont have backup and database not in archive log mode
You loss one datafile and DB is running in ARCHIVELOG mode. You have full database backup of 1 week old and partial backup of this datafile which is just 1 day old. From which backup should you restore this file?
Restore it from Full backup and recover that data file using archive log files which are after Full backup to till date
The current logfile gets damaged. What you can do now?
Once current redolog file is damaged, instance is aborted and it needs recovery upto undamaged part. Only undamaged part can be recovered. Here DBA must apply time based recovery, means it can be a point in time or specified by SCN. It leads to incomplete recovery
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