Database Systems Multiple Choice Questions

In Two-Phase Locking (2PL), a transaction releases locks only after:

• It completes all reads

• It completes all writes

• It has acquired all the locks it needs

• The system restarts

Timestamp ordering protocol prevents:

• Starvation

• Deadlock

• Disk failure

• Phantom reads

Multiversion Concurrency Control (MVCC) maintains:

• One version per transaction

• Multiple versions of data items

• Only the latest version

• No versions

Deadlock occurs when:

• One transaction waits forever for CPU

• Two transactions wait for each other's locks

• A transaction holds locks forever

• A system crash happens

Shadow paging avoids the use of:

• Checkpoints

• Log-based recovery

• Rollback

• Serial scheduling

RAID technology is used for:

• Data encryption

• Compression

• Fault tolerance and performance

• Data partitioning

In a heap file organization, records are stored:

• Sorted by primary key

• Sequentially

• Randomly without any order

• By index order

The data dictionary stores:

• Application data

• Metadata about data

• Backups

• User passwords

Column-oriented storage is most suitable for:

• OLTP systems

• Log files

• Data warehousing and analytics

• Transaction processing

In a B+ tree, actual records are stored in:

• Root nodes

• Internal nodes

• Leaf nodes

• Index nodes only