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After a system crash, what does the recovery system promise about the database state?
Aall committed transactions' effects survive; all uncommitted ones are erased
Ball transactions in progress at crash time are committed automatically
Cthe database reverts to the moment it was created
Dno transactions are aborted; the crash is ignored
Answer & Solution
Correct answer: A. all committed transactions' effects survive; all uncommitted ones are erased
Recovery's job: redo committed work (so durability holds) and undo uncommitted work (so atomicity holds). Automatically committing in-progress transactions would violate atomicity; reverting to creation would lose all work; ignoring the crash would leave dirty pages in place. The redo+undo split is the standard answer.
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