Free Test Concurrency Control Te... – Databas...

Q1: What is the primary goal of concurrency control?

A. To ensure correct execution of concurrent transactions B. To speed up single transactions C. To backup data D. To optimize queries

Q2: Which technique uses locks to control concurrent access?

A. Lock-based concurrency control B. Timestamp ordering C. Optimistic concurrency control D. Two-phase commit

Q3: What is two-phase locking (2PL)?

A. A protocol where all locks are acquired before any are released B. A backup strategy C. A query optimization technique D. A scheduling algorithm

Q4: What problem can arise from two-phase locking?

A. Deadlock B. Data loss C. Backup failure D. Data redundancy

Q5: What does timestamp ordering use to control concurrency?

A. Transaction timestamps to order operations B. Locks C. Logs D. Indexes

Q6: What is optimistic concurrency control?

A. Assuming transactions do not conflict and checking at commit time B. Locking all data items C. Using timestamps for scheduling D. Backing up data

Q7: Which technique is suitable when conflicts are rare?

A. Optimistic concurrency control B. Lock-based control C. Timestamp ordering D. Two-phase commit

Q8: What is a deadlock?

A. A situation where two or more transactions wait indefinitely for each other’s locks B. A transaction failure C. A commit failure D. A backup error

Q9: How can deadlocks be handled?

A. Deadlock detection and rollback B. Ignoring deadlocks C. Restarting the database D. Increasing memory

Q10: What is the purpose of lock granularity?

A. To determine the size of data locked (e.g., row, page, table) B. To choose backup size C. To limit transaction size D. To speed up queries

Q11: What type of lock allows concurrent reads but exclusive writes?

A. Shared lock B. Exclusive lock C. Update lock D. None

Q12: What is an exclusive lock?

A. A lock that allows only one transaction to read/write a data item B. A lock for reading C. A backup lock D. A lock for multiple transactions

Q13: What is a phantom read?

A. New rows are added or removed during a transaction’s execution B. Reading uncommitted data C. Duplicate reads D. Lost updates

Q14: Which isolation level prevents phantom reads?

A. Serializable B. Read Committed C. Read Uncommitted D. Repeatable Read

Q15: What is the difference between shared and exclusive locks?

A. Shared locks allow multiple readers, exclusive locks allow one writer B. Shared locks allow one writer, exclusive allow many readers C. Both allow only one transaction D. No difference

Q16: What does lock escalation mean?

A. Converting multiple fine-grained locks into a coarser lock to reduce overhead B. Increasing lock time C. Unlocking data D. Backing up data

Q17: What is time-stamp ordering protocol used for?

A. Ordering transactions based on timestamps to avoid conflicts B. Locking data C. Backing up data D. Query optimization

Q18: Which concurrency control method does NOT use locks?

A. Optimistic concurrency control B. Two-phase locking C. Strict two-phase locking D. Shared locking

Q19: What is the main disadvantage of pessimistic concurrency control?

A. It can reduce concurrency and cause deadlocks B. It is slower to implement C. Data loss D. No disadvantages

Q20: Which method increases concurrency but requires validation before commit?

A. Optimistic concurrency control B. Two-phase locking C. Timestamp ordering D. Strict locking

Quiz for Concurrency Control Techniques