Transaction Management and Concurrency Control: Master Data Consistency

Question 1

Which transaction property ensures that all changes made to the database either become permanent (committed) or are canceled (rolled back)?

Accepted Answer

Atomicity

Answer

Consistency

Answer

Isolation

Answer

Durability

Question 2

What is the primary function of a deadlock detector?

Accepted Answer

Identifying and resolving deadlocks when they occur

Answer

Preventing deadlocks from happening

Answer

Ensuring that transactions are always executed in a particular order

Answer

Improving the database system's performance

Question 3

Which of the following is a potential drawback of using locking for concurrency control?

Accepted Answer

Can result in deadlocks

Answer

Ensures data consistency

Answer

Prevents starvation

Answer

Supports high levels of concurrency

Question 4

How does logical locking differ from physical locking?

Accepted Answer

Logical locking operates on data items, while physical locking operates on disk pages.

Answer

Physical locking operates on data items, while logical locking operates on disk pages.

Answer

Logical locking is used for read operations, while physical locking is used for write operations.

Answer

There is no difference between logical and physical locking.

Question 5

What does the concept of serializability mean in transaction management?

Accepted Answer

Guaranteeing that the outcome of multiple concurrent transactions is the same as if they were executed in a sequential order

Answer

Preventing deadlocks from occurring

Answer

Maintaining data consistency across multiple transactions

Answer

Improving the performance of the database system

Question 6

What is the purpose of lock-based concurrency control?

Accepted Answer

To prevent multiple transactions from accessing the same data item simultaneously

Answer

To execute transactions in a predetermined order

Answer

To detect and resolve deadlocks

Answer

To ensure data integrity and consistency

Question 7

What is the difference between a read lock and a write lock?

Accepted Answer

Read lock allows shared access, while write lock allows exclusive access

Answer

Write lock allows shared access, while read lock allows exclusive access

Answer

Both read and write locks allow exclusive access

Answer

Both read and write locks allow shared access

Question 8

What is the purpose of the ACID properties?

Accepted Answer

To ensure data consistency and integrity

Answer

To prevent deadlocks

Answer

To improve database performance

Answer

To reduce database overhead

Question 9

What is the difference between a pessimistic and an optimistic locking strategy?

Accepted Answer

Pessimistic locking acquires locks before accessing data, while optimistic locking acquires locks only when needed

Answer

Optimistic locking acquires locks before accessing data, while pessimistic locking acquires locks only when needed

Answer

Both strategies acquire locks before accessing data

Answer

Both strategies acquire locks only when needed

Question 10

Which property is NOT characteristic of transactions in a database system?

Accepted Answer

Reversibility

Answer

Atomicity

Answer

Consistency

Answer

Isolation

Question 11

In a database system, what is the main purpose of a recovery log?

Accepted Answer

To record all database modifications for potential rollback in case of a failure.

Answer

To store a full backup copy of the entire database.

Answer

To track user login and logout activities for auditing purposes.

Answer

To provide performance optimization by caching frequently accessed data.

Question 12

In a database system, what is a deadlock?

Accepted Answer

A situation where two or more transactions are waiting indefinitely for each other to release a lock.

Answer

A type of database failure that results in permanent data loss.

Answer

A performance issue caused by excessive database queries.

Answer

A security vulnerability that allows unauthorized access to data.

Question 13

What is the primary difference between a read lock and a write lock in a database system?

Accepted Answer

A read lock permits multiple transactions to read a data item, while a write lock allows only one transaction to modify it.

Answer

A write lock permits multiple transactions to modify a data item, while a read lock allows only one transaction to read it.

Answer

Read locks are used to prevent deadlocks, while write locks are used to enforce data integrity.

Answer

Write locks are used to prevent lost updates, while read locks are used to prevent dirty reads.

Question 14

What is the primary responsibility of a transaction coordinator in a database system?

Accepted Answer

To coordinate the execution of transactions, ensuring their atomicity and consistency.

Answer

To store and manage data in the database.

Answer

To provide a user interface for accessing and manipulating data.

Answer

To monitor and maintain the overall performance of the database system.

Question 15

What is the primary function of a commit log in a database system?

Accepted Answer

To maintain a record of all committed transactions for recovery purposes.

Answer

To track changes made to the database by individual users.

Answer

To provide a way for users to manually roll back their own transactions.

Answer

To optimize database performance by caching frequently accessed data.

Question 16

What is the primary goal of transaction management in database systems?

Accepted Answer

Ensuring data consistency and integrity

Answer

Enhancing performance

Answer

Optimizing storage space

Answer

Improving security

Question 17

Which ACID property ensures that a transaction is performed without any interference from other transactions?

Accepted Answer

Isolation

Answer

Atomicity

Answer

Consistency

Answer

Durability

Question 18

Which concurrency control mechanism relies on time-stamping to determine the order in which transactions are executed?

Accepted Answer

Timestamp Ordering

Answer

Locking

Answer

Optimistic Concurrency Control

Answer

Two-Phase Locking

Question 19

What type of lock grants exclusive write access to a data item, preventing other transactions from modifying it?

Accepted Answer

Exclusive lock

Answer

Shared lock

Answer

Intention lock

Answer

Update lock

Question 20

What is the significance of a commit point in a transaction?

Accepted Answer

It marks the point where changes made by the transaction become permanent

Answer

It allows other transactions to access updated data

Answer

It releases locks held by the transaction

Answer

It initiates a new transaction

Question 21

Which of the following can potentially lead to deadlocks in a database system?

Accepted Answer

Circular waiting for resources

Answer

Insufficient resources

Answer

Hardware failures

Answer

User errors

Question 22

What is the distinction between logical and physical logs in transaction management?

Accepted Answer

Logical logs record changes to data while physical logs record actual changes to disk

Answer

Logical logs are used for recovery while physical logs are used for auditing

Answer

Physical logs are stored in memory while logical logs are stored on disk

Answer

Logical logs only record committed transactions while physical logs record all changes

Question 23

What is the primary responsibility of a transaction manager in a database system?

Accepted Answer

Coordinating transactions and ensuring data integrity

Answer

Scheduling and executing queries

Answer

Managing user access and permissions

Answer

Optimizing database performance

Question 24

Which of the following is NOT a property of ACID transactions?

Accepted Answer

Reversibility

Answer

Atomicity

Answer

Consistency

Answer

Isolation

Question 25

What is the main purpose of using locks in a database management system?

Accepted Answer

To prevent concurrent access to shared data and maintain data integrity

Answer

To ensure efficient data retrieval

Answer

To improve database performance

Answer

To facilitate data backup and recovery

Question 26

Which of the following concurrency control techniques assigns timestamps to transactions to determine their execution order?

Accepted Answer

Timestamp-based concurrency control

Answer

Optimistic concurrency control

Answer

Pessimistic concurrency control

Answer

Two-phase locking

Question 27

What is a key advantage of using optimistic concurrency control?

Accepted Answer

Reduced locking overhead, leading to improved performance

Answer

Guaranteed conflict resolution

Answer

Reduced data integrity issues

Answer

Simplified transaction management

Question 28

What is the primary function of a recovery log in a database management system?

Accepted Answer

To record all database modifications and transactions to enable recovery in case of system failures

Answer

To store backup copies of database data

Answer

To improve database performance by caching frequently accessed data

Answer

To facilitate data migration between different database systems

Question 29

What is a major advantage of using distributed transactions?

Accepted Answer

Improved data consistency across multiple databases involved in the transaction

Answer

Reduced transaction processing time

Answer

Elimination of potential data integrity issues

Answer

Simplified transaction management and reduced complexity

Question 30

Which of the following is NOT a key property of ACID transactions?

Accepted Answer

Concurrency

Answer

Atomicity

Answer

Consistency

Answer

Isolation

Question 31

What is the primary purpose of using locks in concurrency control?

Accepted Answer

To prevent concurrent access to data, ensuring data integrity

Answer

To grant exclusive access to data, allowing multiple transactions to modify it simultaneously

Answer

To improve the performance of queries by reducing lock contention

Answer

To detect and resolve deadlocks

Question 32

What is the purpose of a timestamp in timestamp-based concurrency control?

Accepted Answer

To uniquely identify and order transactions, resolving conflicts based on their timestamps

Answer

To determine the most recent version of a data item

Answer

To detect and prevent deadlocks by aborting the transaction with the oldest timestamp

Answer

To improve the performance of query processing

Question 33

What is the primary purpose of a transaction log in a database management system?

Accepted Answer

To record all database modifications made within a transaction, enabling recovery in case of failures

Answer

To provide a complete backup of the database for disaster recovery purposes

Answer

To improve the performance of queries by caching frequently accessed data

Answer

To manage user access permissions and control database security

Question 34

Which of the following is **not** a property of ACID transactions?

Accepted Answer

Reversibility

Answer

Durability

Answer

Isolation

Answer

Consistency

Question 35

What is the primary responsibility of a lock manager in a database system?

Accepted Answer

To prevent concurrent transactions from accessing the same data simultaneously

Answer

To optimize data retrieval

Answer

To handle transaction rollback

Answer

To manage database storage

Question 36

What is the primary cause of a deadlock in concurrency control?

Accepted Answer

Circular waiting among multiple transactions for resources held by each other

Answer

A normal state in a database system

Answer

An error that occurs when a transaction fails

Question 37

Which benefit do timestamps provide in concurrency control?

Accepted Answer

Preventing phantom reads by validating the read timestamp against the transaction's start timestamp

Answer

Reducing transaction overhead

Answer

Allowing long-running transactions to complete without blocking

Answer

Eliminating deadlocks

Question 38

Explain the difference between 'commit' and 'rollback' in transaction management.

Accepted Answer

Commit makes changes permanent and durable, while rollback reverses the changes to restore the database to its previous state

Answer

Rollback makes changes permanent while commit reverts them

Answer

Commit and rollback are the same operation

Question 39

Which isolation level allows transactions to read uncommitted data written by other transactions?

Accepted Answer

Read Uncommitted

Answer

Read Committed

Answer

Repeatable Read

Answer

Serializable

Question 40

What is the main purpose of a commit log in a database?

Accepted Answer

To provide durability by ensuring that committed transactions are not lost even in the event of a system failure

Answer

To handle transaction rollback

Answer

To store database indexes

Answer

To store user queries

Question 41

Which type of concurrency control technique relies on validation at the end of a transaction?

Accepted Answer

Timestamp-based Optimistic Concurrency Control

Answer

Two-Phase Locking

Answer

Repeatable Read

Answer

Read Committed

Question 42

What is a potential advantage of using multi-version concurrency control?

Accepted Answer

Increased concurrency by allowing multiple versions of the same data to exist simultaneously, reducing write conflicts

Answer

Eliminating deadlocks

Answer

Reducing transaction overhead

Question 43

Which ACID property ensures that a transaction's changes are permanently recorded in the database if it completes successfully?

Accepted Answer

Durability

Answer

Atomicity

Answer

Consistency

Question 44

What type of concurrency control issue occurs when a transaction reads data that has been partially modified by another transaction but not yet committed?

Accepted Answer

Dirty Read

Answer

Phantom Read

Answer

Non-Repeatable Read

Answer

Lost Update

Question 45

Which of the following is NOT a common concurrency control technique?

Accepted Answer

Timestamp Ordering

Answer

Optimistic Concurrency Control

Answer

Multiversion Concurrency Control

Answer

Two-Phase Locking

Question 46

In a system using optimistic concurrency control, when is conflict detection typically performed?

Accepted Answer

Before a transaction commits its changes

Answer

At the beginning of the transaction

Answer

During each read operation

Answer

After a transaction commits its changes

Question 47

What is the primary function of a lock manager in a database system?

Accepted Answer

Manages the granting and releasing of locks on data items

Answer

Optimizes query execution plans for improved performance

Answer

Logs all database transactions for recovery purposes

Question 48

Which isolation level prevents dirty reads, non-repeatable reads, and phantom reads?

Accepted Answer

Serializable

Answer

Repeatable Read

Answer

Read Committed

Answer

Read Uncommitted

Question 49

A schedule of database operations is considered serializable if it:

Accepted Answer

Produces the same final database state as if the transactions were executed one after the other in some order

Answer

Ensures that no two transactions access the same data item simultaneously

Answer

Executes all transactions sequentially

Question 50

What is the main purpose of a checkpoint in database recovery?

Accepted Answer

To minimize the amount of log data that needs to be scanned during recovery

Answer

To improve query performance

Answer

To prevent database crashes

Question 51

Which of the following is a potential drawback of using two-phase locking for concurrency control?

Accepted Answer

It can lead to deadlocks

Answer

It is inefficient for read-only transactions

Answer

It allows dirty reads

Answer

It increases the risk of data corruption

Question 52

What does the acronym "WAL" stand for in the context of database management systems?

Accepted Answer

Write-Ahead Logging

Answer

Web Application Logic

Answer

Wide Area Latency

Answer

Wait and Lock