Which three statements are true about the database instance startup after an instance failure?
A.
The RECO process recovers the uncommitted transactions at the next instance startup.
B.
Online redo log files and archived redo log files are required to complete the rollback stage of instance
recovery.
C.
Uncommitted changes are rolled back to ensure transactional consistency.
D.
The SMON process coordinates the database recovery.
E.
Media recovery is required to complete the database recovery.
F.
Changes committed before the failure, which were not written to the data files, are re-applied.
Explanation:
A: Occasionally a database closes abnormally with one or more distributed transactions in doubt (neither committed nor rolled back). When you reopen the database and recovery is complete, the RECO background process automatically, immediately, and consistently resolves any in-doubt distributed transactions.
C: Crash and instance recovery involve two distinct operations: rolling forward the current, online datafiles by applying both committed and uncommitted transactions contained in online redo records, and then rolling back changes made in uncommitted transactions to their original state.
D: The SMON background process performs instance recovery, applying online redo automatically. No user intervention is required.
References:
https://docs.oracle.com/cd/B28359_01/server.111/b28318/startup.htm https://docs.oracle.com/database/121/CNCPT/startup.htm
CDF