When users inform the DBA that a resource is unavailable or that queries are not responding, which views should the DBA use to determine the locking and waiting sessions? (Choose two.)
A . V$BLOCK_AND_WAIT
B. DBA_BLOCKERS
C . DBA_LOCKS_HELD
D . V$SESSIONS_WAITING
E. DBA_WAITERS
Explanation:
Answer B and E: The DBA_BLOCKERS and DBA_WAITERS views are used to determine who is causing lock contention, and who is waiting on lock requests. DBA_LOCKS can be used, but the DBA_BLOCKERS and DBA_WAITERS views are pre-defined to display the basic information needed for problem resolution. V$SESSIONS_WAITING and V$BLOCK_AND_WAIT are not valid views.
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