Database Systems: Design,
Implementation & Management 12e
Chapter 10 2026/ 2027 – Q&A Study
Guide & Practice Questions
Question 1: ACID Properties
Which of the ACID properties ensures that once a transaction is successfully completed and
committed, its database changes survive a system crash or power failure?
• A. Atomicity
• B. Consistency
• C. Isolation
• D. Durability
• Correct Answer: D. Durability
• Rationale: Durability guarantees that committed transaction changes are permanently
recorded in non-volatile storage, ensuring they are not lost during subsequent system
failures.
Question 2: Concurrency Control Anomalies
An anomaly that occurs when Transaction A retrieves data that is subsequently updated and
committed by Transaction B, causing Transaction A to read two different values for the same
data item during a single run, is known as:
• A. Lost Update
• B. Dirty Read
• C. Non-repeatable Read (Inconsistent Retrieval)
• D. Deadlock
• Correct Answer: C. Non-repeatable Read (Inconsistent Retrieval)
• Rationale: A non-repeatable read happens when a transaction reads the same row twice
while another concurrent transaction modifies and commits changes to that row in
between reads, resulting in differing values.
Question 3: Two-Phase Locking Protocol
,What is the primary characteristic of the shrinking phase in a Two-Phase Locking (2PL)
protocol?
• A. Transactions can acquire new locks as needed.
• B. Transactions can release locks, but no new locks can be acquired.
• C. Transactions execute without any locks.
• D. Transactions are aborted automatically.
• Correct Answer: B. Transactions can release locks, but no new locks can be
acquired.
• Rationale: In the shrinking phase of 2PL, existing locks are released sequentially, and no
additional locks can be requested, preventing serializability violations.
Question 4: Deadlock Management
Which strategy handles deadlocks by evaluating lock requests and aborting a transaction if a
cycle or potential wait-for dependency creates an unresolvable stall?
• A. Deadlock prevention
• B. Deadlock avoidance
• C. Deadlock detection
• D. Timestamp ordering
• Correct Answer: C. Deadlock detection
• Rationale: Deadlock detection allows deadlocks to occur, periodically uses a wait-for
graph to check for circular waiting loops, and breaks the deadlock by rolling back one of
the participating transactions.
Question 5: Database Recovery
Under the Write-Ahead Log (WAL) protocol, what must happen before a database data block is
modified on disk?
• A. The user must log out of the system.
• B. The corresponding log records describing the change must be written to stable storage.
• C. A database backup must be created on tape.
• D. All locks must be released.
• Correct Answer: B. The corresponding log records describing the change must be
written to stable storage.
• Rationale: WAL mandates that transaction logs detailing modifications are safely written
to disk before the actual database pages are updated, ensuring rollback and recovery
capabilities.
Short-Answer Questions
, Question 6: Explain the difference between a Shared (S) Lock and an Exclusive (X) Lock.
• Answer:
o A Shared (S) Lock is granted when a transaction wants to read data. Multiple
transactions can hold shared locks on the same data item simultaneously because
reading does not alter data.
o An Exclusive (X) Lock is granted when a transaction wants to update (write)
data. Only one transaction can hold an exclusive lock on a data item, and no other
transaction can read or write that item until the exclusive lock is released.
Question 7: What are the three primary database failure types that database recovery
management must handle?
• Answer:
1. Transaction failures: Errors internal to a transaction (e.g., logical errors, syntax
issues, constraint violations) that cause it to abort voluntarily.
2. System failures: Hardware crashes, operating system failures, or power outages
that halt volatile memory (RAM) operations.
3. Media failures: Permanent physical damage to storage media (e.g., disk crashes,
head crashes) requiring restoration from backups and logs.
Question 8: Serializability
What is the primary objective of a serializable schedule in transaction management?
• A. To ensure transactions execute one after another in a random sequence.
• B. To guarantee that a concurrent execution of transactions produces the same database
state as if the transactions had executed serially one-at-a-time.
• C. To maximize hardware CPU utilization by running queries in parallel without logs.
• D. To prevent users from logging into the database simultaneously.
• Correct Answer: B. To guarantee that a concurrent execution of transactions
produces the same database state as if the transactions had executed serially one-at-
a-time.
• Rationale: Serializability is the gold standard of concurrency control. It ensures that even
though transactions overlap in time, the final result is identical to some purely serial
execution, preserving data consistency.
Question 9: Lock Granularity
Which lock granularity level imposes the lowest locking overhead on the DBMS but provides the
highest degree of conflict/blocking among transactions?
• A. Row-level lock
• B. Page-level lock
• C. Table-level lock
Implementation & Management 12e
Chapter 10 2026/ 2027 – Q&A Study
Guide & Practice Questions
Question 1: ACID Properties
Which of the ACID properties ensures that once a transaction is successfully completed and
committed, its database changes survive a system crash or power failure?
• A. Atomicity
• B. Consistency
• C. Isolation
• D. Durability
• Correct Answer: D. Durability
• Rationale: Durability guarantees that committed transaction changes are permanently
recorded in non-volatile storage, ensuring they are not lost during subsequent system
failures.
Question 2: Concurrency Control Anomalies
An anomaly that occurs when Transaction A retrieves data that is subsequently updated and
committed by Transaction B, causing Transaction A to read two different values for the same
data item during a single run, is known as:
• A. Lost Update
• B. Dirty Read
• C. Non-repeatable Read (Inconsistent Retrieval)
• D. Deadlock
• Correct Answer: C. Non-repeatable Read (Inconsistent Retrieval)
• Rationale: A non-repeatable read happens when a transaction reads the same row twice
while another concurrent transaction modifies and commits changes to that row in
between reads, resulting in differing values.
Question 3: Two-Phase Locking Protocol
,What is the primary characteristic of the shrinking phase in a Two-Phase Locking (2PL)
protocol?
• A. Transactions can acquire new locks as needed.
• B. Transactions can release locks, but no new locks can be acquired.
• C. Transactions execute without any locks.
• D. Transactions are aborted automatically.
• Correct Answer: B. Transactions can release locks, but no new locks can be
acquired.
• Rationale: In the shrinking phase of 2PL, existing locks are released sequentially, and no
additional locks can be requested, preventing serializability violations.
Question 4: Deadlock Management
Which strategy handles deadlocks by evaluating lock requests and aborting a transaction if a
cycle or potential wait-for dependency creates an unresolvable stall?
• A. Deadlock prevention
• B. Deadlock avoidance
• C. Deadlock detection
• D. Timestamp ordering
• Correct Answer: C. Deadlock detection
• Rationale: Deadlock detection allows deadlocks to occur, periodically uses a wait-for
graph to check for circular waiting loops, and breaks the deadlock by rolling back one of
the participating transactions.
Question 5: Database Recovery
Under the Write-Ahead Log (WAL) protocol, what must happen before a database data block is
modified on disk?
• A. The user must log out of the system.
• B. The corresponding log records describing the change must be written to stable storage.
• C. A database backup must be created on tape.
• D. All locks must be released.
• Correct Answer: B. The corresponding log records describing the change must be
written to stable storage.
• Rationale: WAL mandates that transaction logs detailing modifications are safely written
to disk before the actual database pages are updated, ensuring rollback and recovery
capabilities.
Short-Answer Questions
, Question 6: Explain the difference between a Shared (S) Lock and an Exclusive (X) Lock.
• Answer:
o A Shared (S) Lock is granted when a transaction wants to read data. Multiple
transactions can hold shared locks on the same data item simultaneously because
reading does not alter data.
o An Exclusive (X) Lock is granted when a transaction wants to update (write)
data. Only one transaction can hold an exclusive lock on a data item, and no other
transaction can read or write that item until the exclusive lock is released.
Question 7: What are the three primary database failure types that database recovery
management must handle?
• Answer:
1. Transaction failures: Errors internal to a transaction (e.g., logical errors, syntax
issues, constraint violations) that cause it to abort voluntarily.
2. System failures: Hardware crashes, operating system failures, or power outages
that halt volatile memory (RAM) operations.
3. Media failures: Permanent physical damage to storage media (e.g., disk crashes,
head crashes) requiring restoration from backups and logs.
Question 8: Serializability
What is the primary objective of a serializable schedule in transaction management?
• A. To ensure transactions execute one after another in a random sequence.
• B. To guarantee that a concurrent execution of transactions produces the same database
state as if the transactions had executed serially one-at-a-time.
• C. To maximize hardware CPU utilization by running queries in parallel without logs.
• D. To prevent users from logging into the database simultaneously.
• Correct Answer: B. To guarantee that a concurrent execution of transactions
produces the same database state as if the transactions had executed serially one-at-
a-time.
• Rationale: Serializability is the gold standard of concurrency control. It ensures that even
though transactions overlap in time, the final result is identical to some purely serial
execution, preserving data consistency.
Question 9: Lock Granularity
Which lock granularity level imposes the lowest locking overhead on the DBMS but provides the
highest degree of conflict/blocking among transactions?
• A. Row-level lock
• B. Page-level lock
• C. Table-level lock
