June 12, 2011 at 5:36 am
What is backward recovery/undo and roll forward and rollback
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Going in one more round when you don't think you can - that's what makes all the difference in your life --Rocky Balboa
Believe you can and you're halfway there. --Theodore Roosevelt
I can't tell you what backward recovery is, never heard of that one.
Rollback or rollforward is referring to transactions. A rollback on a transaction is to undo whatever that transaction has done. A rollforward would be to apply a given transaction, making it do what it had done already. Rollback can be referring to coded transactions or to the recovery process at the end of a restore operation. Rollforward is referring to the recovery process.
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To add to Grant, when you restore a database, or a log, the engine does redo/undo, which is essentially rolling forward and rolling back. Items in the log that were not changed in the data files are "redo"ne, or rolled forward so the log and data files are in a consistent state. Items that were flushed to the log, but not committed, are "undo"ne, or rolled back.
A rollback is typically different, as Grant mentioned.
Never heard of backward recovery.
thanks both for the replies
____________________________________________________________________
Going in one more round when you don't think you can - that's what makes all the difference in your life --Rocky Balboa
Believe you can and you're halfway there. --Theodore Roosevelt
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