Practice Library
All MCQs
Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
Choose an option to check your answer.
A.
a strategy that never uses timestamps
B.
a method used only for file compression
C.
a strategy that avoids deadlocks before they occur using rules such as wait-die or wound-wait
D.
a method that deletes all waiting transactions randomly
Show Answer
Correct Answer: C. a strategy that avoids deadlocks before they occur using rules such as wait-die or wound-wait
Explanation:
deadlock prevention is used in Advanced DBMS because a strategy that avoids deadlocks before they occur using rules such as wait-die or wound-wait.
Choose an option to check your answer.
A.
a type of B-tree split
B.
a MongoDB collection validator only
C.
a recovery point that reduces the amount of log scanning after a crash
D.
a password reset operation
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Correct Answer: C. a recovery point that reduces the amount of log scanning after a crash
Explanation:
This statement is correct because checkpoint means that a recovery point that reduces the amount of log scanning after a crash.
Choose an option to check your answer.
A.
a graph used to test conflict serializability by checking cycles
B.
a graph used to encrypt user passwords
C.
a diagram used only for ER modeling
D.
a MongoDB replication topology only
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Correct Answer: A. a graph used to test conflict serializability by checking cycles
Explanation:
The correct answer explains precedence graph in the context of Transactions.
Choose an option to check your answer.
A.
a transaction has a growing phase for acquiring locks and a shrinking phase for releasing locks
B.
locks are used only for backup files
C.
all transactions execute without locks
D.
locks are acquired and released randomly
Show Answer
Correct Answer: A. a transaction has a growing phase for acquiring locks and a shrinking phase for releasing locks
Explanation:
two-phase locking is used in Advanced DBMS because a transaction has a growing phase for acquiring locks and a shrinking phase for releasing locks.
Choose an option to check your answer.
A.
a method used only for file compression
B.
a strategy that never uses timestamps
C.
a strategy that avoids deadlocks before they occur using rules such as wait-die or wound-wait
D.
a method that deletes all waiting transactions randomly
Show Answer
Correct Answer: C. a strategy that avoids deadlocks before they occur using rules such as wait-die or wound-wait
Explanation:
This statement is correct because deadlock prevention means that a strategy that avoids deadlocks before they occur using rules such as wait-die or wound-wait.
Choose an option to check your answer.
A.
creates a secondary index
B.
reapplies committed updates during recovery to ensure durability
C.
removes every committed transaction
D.
blocks all future transactions
Show Answer
Correct Answer: B. reapplies committed updates during recovery to ensure durability
Explanation:
The correct answer explains redo operation in the context of Recovery.
Choose an option to check your answer.
A.
a hash function maps search key values to storage buckets
B.
transactions are executed on replicas only
C.
all data is stored in the recovery log
D.
records are sorted using B-tree leaves only
Show Answer
Correct Answer: A. a hash function maps search key values to storage buckets
Explanation:
hash file organization is used in Advanced DBMS because a hash function maps search key values to storage buckets.
Choose an option to check your answer.
A.
an index entry for every record in the file
B.
a table without any rows
C.
an index that stores entries for some search key values, usually one per block
D.
a trigger that fires after commit
Show Answer
Correct Answer: C. an index that stores entries for some search key values, usually one per block
Explanation:
This statement is correct because sparse index means that an index that stores entries for some search key values, usually one per block.
Choose an option to check your answer.
A.
concurrent transactions should not interfere in a way that violates correctness
B.
transactions are physically stored on separate disks only
C.
tables are separated from indexes
D.
all database users work offline
Show Answer
Correct Answer: A. concurrent transactions should not interfere in a way that violates correctness
Explanation:
The correct answer explains isolation in the context of Transactions.
Choose an option to check your answer.
A.
a hash function maps search key values to storage buckets
B.
records are sorted using B-tree leaves only
C.
all data is stored in the recovery log
D.
transactions are executed on replicas only
Show Answer
Correct Answer: A. a hash function maps search key values to storage buckets
Explanation:
This statement is correct because hash file organization means that a hash function maps search key values to storage buckets.
Choose an option to check your answer.
A.
a lock that blocks all readers permanently
B.
a balanced tree index in which data pointers are commonly stored at leaf level
C.
a sequential log for transaction recovery
D.
a password hashing mechanism
Show Answer
Correct Answer: B. a balanced tree index in which data pointers are commonly stored at leaf level
Explanation:
The correct answer explains B+ tree index in the context of File Organization.
Choose an option to check your answer.
A.
tables are separated from indexes
B.
concurrent transactions should not interfere in a way that violates correctness
C.
all database users work offline
D.
transactions are physically stored on separate disks only
Show Answer
Correct Answer: B. concurrent transactions should not interfere in a way that violates correctness
Explanation:
isolation is used in Advanced DBMS because concurrent transactions should not interfere in a way that violates correctness.
