Practice Library
All MCQs
Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
Choose an option to check your answer.
A.
users need not know how relations are fragmented across sites
B.
users must join fragments manually every time
C.
fragments cannot be reconstructed
D.
fragments must be encrypted only
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Correct Answer: A. users need not know how relations are fragmented across sites
Explanation:
fragmentation transparency is used in Advanced DBMS because users need not know how relations are fragmented across sites.
Choose an option to check your answer.
A.
coordinating concurrent transactions that access data at multiple sites
B.
running all transactions without isolation
C.
using only a single local lock table always
D.
denying every remote read
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Correct Answer: A. coordinating concurrent transactions that access data at multiple sites
Explanation:
This statement is correct because distributed concurrency control means that coordinating concurrent transactions that access data at multiple sites.
Choose an option to check your answer.
A.
storing all data in one central table
B.
deleting the primary key from every fragment
C.
splitting a relation by columns while preserving a way to reconstruct it
D.
splitting a relation by rows only
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Correct Answer: C. splitting a relation by columns while preserving a way to reconstruct it
Explanation:
vertical fragmentation is used in Advanced DBMS because splitting a relation by columns while preserving a way to reconstruct it.
Choose an option to check your answer.
A.
users must join fragments manually every time
B.
fragments must be encrypted only
C.
users need not know how relations are fragmented across sites
D.
fragments cannot be reconstructed
Show Answer
Correct Answer: C. users need not know how relations are fragmented across sites
Explanation:
This statement is correct because fragmentation transparency means that users need not know how relations are fragmented across sites.
Choose an option to check your answer.
A.
NoSQL databases cannot be replicated
B.
every database must use only SQL
C.
indexes always remove the need for consistency
D.
a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition
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Correct Answer: D. a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition
Explanation:
The correct answer explains CAP theorem in the context of Distributed Databases.
Choose an option to check your answer.
A.
splitting a relation by rows only
B.
deleting the primary key from every fragment
C.
storing all data in one central table
D.
splitting a relation by columns while preserving a way to reconstruct it
Show Answer
Correct Answer: D. splitting a relation by columns while preserving a way to reconstruct it
Explanation:
This statement is correct because vertical fragmentation means that splitting a relation by columns while preserving a way to reconstruct it.
Choose an option to check your answer.
A.
replication always prevents consistency
B.
users need not know which copy of replicated data is being accessed
C.
replicas are invisible to the DBMS only
D.
users must update every copy manually
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Correct Answer: B. users need not know which copy of replicated data is being accessed
Explanation:
The correct answer explains replication transparency in the context of Distributed Databases.
Choose an option to check your answer.
A.
a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition
B.
NoSQL databases cannot be replicated
C.
indexes always remove the need for consistency
D.
every database must use only SQL
Show Answer
Correct Answer: A. a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition
Explanation:
CAP theorem is used in Advanced DBMS because a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition.
Choose an option to check your answer.
A.
storing copies of data at multiple sites to improve availability or performance
B.
removing all indexes from a database
C.
storing one copy only on a single server
D.
executing all queries without transactions
Show Answer
Correct Answer: A. storing copies of data at multiple sites to improve availability or performance
Explanation:
The correct answer explains replication in the context of Distributed Databases.
Choose an option to check your answer.
A.
users must update every copy manually
B.
users need not know which copy of replicated data is being accessed
C.
replication always prevents consistency
D.
replicas are invisible to the DBMS only
Show Answer
Correct Answer: B. users need not know which copy of replicated data is being accessed
Explanation:
replication transparency is used in Advanced DBMS because users need not know which copy of replicated data is being accessed.
Choose an option to check your answer.
A.
every database must use only SQL
B.
NoSQL databases cannot be replicated
C.
a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition
D.
indexes always remove the need for consistency
Show Answer
Correct Answer: C. a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition
Explanation:
This statement is correct because CAP theorem means that a distributed system cannot simultaneously guarantee strong consistency, availability, and partition tolerance under network partition.
Choose an option to check your answer.
A.
storing one copy only on a single server
B.
executing all queries without transactions
C.
storing copies of data at multiple sites to improve availability or performance
D.
removing all indexes from a database
Show Answer
Correct Answer: C. storing copies of data at multiple sites to improve availability or performance
Explanation:
replication is used in Advanced DBMS because storing copies of data at multiple sites to improve availability or performance.
