What is a transaction in a database context?
A) A set of database operations that must all succeed or fail together
B) A report generated from the database
C) A backup of the database
D) A data structure that improves data retrieval speed
Answer: A
Which property of transactions ensures that all changes made by a transaction are either committed or rolled back?
A) Atomicity
B) Consistency
C) Isolation
D) Durability
Answer: A
What does ACID stand for in the context of database transactions?
A) Atomicity, Continuity, Isolation, Durability
B) Atomicity, Consistency, Isolation, Durability
C) Association, Consistency, Isolation, Durability
D) Association, Continuity, Isolation, Durability
Answer: B
Which of the following is a property of a transaction that ensures that it leaves the database in a consistent state?
A) Atomicity
B) Consistency
C) Isolation
D) Durability
Answer: B
What is isolation in the context of database transactions?
A) Ensuring that all changes made by a transaction are either committed or rolled back
B) Ensuring that transactions execute independently without interfering with each other
C) Ensuring that transactions are durable and not lost
D) Ensuring that transactions are executed in a certain order
Answer: B
Which isolation level ensures that a transaction can only read committed data and prevents dirty reads?
A) Read Uncommitted
B) Read Committed
C) Repeatable Read
D) Serializable
Answer: B
What is a dirty read in the context of database transactions?
A) Reading data that has been modified by another uncommitted transaction
B) Reading data that is not stored in the database
C) Reading data that is stored in a separate table
D) Reading data that is encrypted
Answer: A
Which of the following is a technique used to manage concurrent access to data in a database?
A) Transaction log
B) Locking
C) Query optimization
D) Indexing
Answer: B
What is a lock in the context of concurrency control?
A) A mechanism to prevent data from being accessed by multiple transactions simultaneously
B) A mechanism to encrypt data
C) A mechanism to store data temporarily
D) A mechanism to delete data from the database
Answer: A
Which of the following is a disadvantage of using locks for concurrency control?
A) Increased data consistency
B) Deadlock possibility
C) Improved data integrity
D) Reduced transaction isolation
Answer: B
What is deadlock in the context of concurrency control?
A) A situation where transactions wait indefinitely for each other to release locks
B) A situation where transactions commit simultaneously
C) A situation where transactions roll back automatically
D) A situation where transactions are isolated from each other
Answer: A
Which of the following is a strategy to avoid deadlock in a database system?
A) Increasing transaction isolation level
B) Using optimistic concurrency control
C) Using shared locks
D) Implementing timeout mechanisms
Answer: D
What is optimistic concurrency control?
A) A strategy where transactions assume that conflicts are rare and do not use locks
B) A strategy where transactions use locks for every data access
C) A strategy where transactions use exclusive locks
D) A strategy where transactions use shared locks
Answer: A
Which of the following is true about pessimistic concurrency control?
A) It assumes that conflicts are rare and does not use locks
B) It assumes that conflicts are common and uses locks to prevent them
C) It does not allow transactions to execute concurrently
D) It allows transactions to read uncommitted data
Answer: B
What is a deadlock prevention technique that involves ordering resources and requiring that transactions obtain resources in order?
A) Timeout mechanism
B) Two-phase locking
C) Deadlock detection
D) Strict two-phase locking
Answer: D
Which of the following concurrency control techniques ensures that all locks held by a transaction are released only after the transaction is committed or rolled back?
A) Two-phase locking
B) Timeout mechanism
C) Deadlock prevention
D) Serializability
Answer: A
What is the purpose of serializability in database transactions?
A) To ensure that transactions are durable
B) To ensure that transactions execute in a specific order
C) To ensure that transactions do not interfere with each other
D) To ensure that transactions are consistent
Answer: C
Which of the following is a benefit of using transactions in a database system?
A) Reduced data integrity
B) Improved data redundancy
C) Atomicity of operations
D) Increased complexity of queries
Answer: C
What is the purpose of durability in the ACID properties of transactions?
A) To ensure that transactions are isolated from each other
B) To ensure that all changes made by a committed transaction are permanent
C) To ensure that transactions execute in a specific order
D) To ensure that transactions do not interfere with each other
Answer: B
Which of the following is a disadvantage of using optimistic concurrency control?
A) Increased deadlock possibility
B) Reduced transaction isolation
C) Inability to handle conflicts
D) Increased complexity of implementation
Answer: C
What is a transaction log in a database system?
A) A log of all transactions that have been executed
B) A log of all indexes created in the database
C) A log of all database backups
D) A log of all SQL queries executed
Answer: A
Which of the following is true about transaction logs?
A) Transaction logs are used only for auditing purposes
B) Transaction logs are used to restore a database to a previous state after a crash
C) Transaction logs are created automatically by the database system
D) Transaction logs store only committed transactions
Answer: B
What is a savepoint in the context of database transactions?
A) A point in a transaction where changes can be rolled back without affecting the entire transaction
B) A point in a transaction where changes are automatically committed
C) A point in a transaction where locks are released
D) A point in a transaction where deadlock occurs
Answer: A
Which of the following is a benefit of using savepoints in transactions?
A) Improved data redundancy
B) Increased complexity of queries
C) Enhanced transaction flexibility
D) Reduced data consistency
Answer: C
What is the purpose of a transaction manager in a database system?
A) To manage database backups
B) To manage database indexes
C) To manage database transactions and ensure ACID properties
D) To manage database schema changes
Answer: C
Which of the following is a role of a transaction manager?
A) Creating new indexes
B) Handling transaction logs
C) Optimizing SQL queries
D) Reducing data redundancy
Answer: B
What is the primary responsibility of a transaction coordinator in a distributed database system?
A) To ensure that all transactions are isolated from each other
B) To ensure that all transactions execute in a specific order
C) To ensure that all transactions have the same isolation level
D) To ensure that all transactions follow the ACID properties
Answer: D
Which of the following is true about distributed transactions?
A) Distributed transactions are always faster than centralized transactions
B) Distributed transactions do not require concurrency control
C) Distributed transactions involve multiple databases
D) Distributed transactions cannot ensure data consistency
Answer: C
What is two-phase commit protocol in the context of distributed transactions?
A) A protocol where transactions are committed in two phases to ensure data consistency across multiple databases
B) A protocol where transactions are executed in two phases to ensure data isolation
C) A protocol where transactions are rolled back in two phases to handle deadlock
D) A protocol where transactions are audited in two phases to handle data redundancy
Answer: A
Which of the following is a challenge in managing distributed transactions?
A) Reduced complexity
B) Increased data redundancy
C) Network latency
D) Improved data isolation
Answer: C
What is the purpose of a distributed transaction coordinator?
A) To manage transaction logs
B) To manage distributed transactions and ensure data consistency
C) To manage database indexes
D) To manage database schema changes
Answer: B
Which of the following is true about distributed transaction coordinators?
A) They are only used in centralized databases
B) They manage transactions in a distributed database environment
C) They do not support ACID properties
D) They do not use concurrency control
Answer: B
What is a transaction boundary in the context of database transactions?
A) A boundary that separates data from metadata
B) A boundary that separates different database tables
C) A boundary that separates one transaction from another
D) A boundary that separates database backups
Answer: C
Which of the following is true about transaction boundaries?
A) They are static and cannot be changed
B) They are dynamic and can be adjusted based on transaction requirements
C) They are defined by database indexes
D) They are used for creating savepoints
Answer: B
What is the purpose of transaction boundaries in a database system?
A) To prevent data redundancy
B) To ensure data isolation
C) To improve query performance
D) To manage database schema changes
Answer: B
Which of the following is a benefit of using transaction boundaries?
A) Reduced data consistency
B) Increased transaction complexity
C) Enhanced data integrity
D) Decreased transaction isolation
Answer: C
What is a nested transaction in the context of database transactions?
A) A transaction that is executed after another transaction
B) A transaction that contains one or more sub-transactions
C) A transaction that is rolled back automatically
D) A transaction that does not use locks
Answer: B
Which of the following is true about nested transactions?
A) They are not supported by database systems
B) They allow sub-transactions to commit or roll back independently of the main transaction
C) They can only be used with optimistic concurrency control
D) They increase the likelihood of deadlock
Answer: B
What is the purpose of a distributed lock manager in a distributed database system?
A) To manage distributed transactions
B) To manage database indexes
C) To manage database schema changes
D) To manage locks on resources across multiple databases
Answer: D
Which of the following is true about distributed lock managers?
A) They do not support concurrency control
B) They ensure that only one transaction can access a resource at a time
C) They do not use transaction boundaries
D) They do not support ACID properties
Answer: B
What is the purpose of a transaction scheduler in a database system?
A) To manage transaction logs
B) To manage database indexes
C) To manage distributed transactions
D) To schedule transactions for execution
Answer: D
Which of the following is true about transaction schedulers?
A) They are used to optimize query performance
B) They do not use concurrency control
C) They ensure that transactions execute in a specific order
D) They do not use transaction boundaries
Answer: C
What is a transaction state in a database system?
A) The current state of a transaction, including whether it is active, committed, or rolled back
B) The current state of a database, including its size and location
C) The current state of a transaction log
D) The current state of a distributed database
Answer: A
Which of the following is true about transaction states?
A) They do not include transaction boundaries
B) They do not affect data consistency
C) They are static and cannot change
D) They are dynamic and change as transactions progress
Answer: D
What is transaction management in the context of database transactions?
A) Managing database indexes
B) Managing database schema changes
C) Managing transaction boundaries and ensuring ACID properties
D) Managing database backups
Answer: C
Which of the following is true about transaction management?
A) It does not involve concurrency control
B) It is only used in distributed databases
C) It is independent of transaction boundaries
D) It ensures that transactions follow the ACID properties
Answer: D
What is transaction control in the context of database transactions?
A) Controlling database backups
B) Controlling database schema changes
C) Controlling transaction boundaries and ensuring ACID properties
D) Controlling database indexes
Answer: C
Which of the following is true about transaction control?
A) It does not involve concurrency control
B) It is only used in distributed databases
C) It is independent of transaction boundaries
D) It ensures that transactions follow the ACID properties
Answer: D
What is transaction scheduling in the context of database transactions?
A) Scheduling database backups
B) Scheduling database schema changes
C) Scheduling transaction execution and ensuring ACID properties
D) Scheduling database indexes
Answer: C
Which of the following is true about transaction scheduling?
A) It does not involve concurrency control
B) It is only used in distributed databases
C) It is independent of transaction boundaries
D) It ensures that transactions follow the ACID properties
Answer: D