Database Recovery Techniques - recovery management, backup and restore strategies - One Line Questions

1. What is a 'hot backup' in database terminology? — A backup taken while the database is online and operational
2. What is a 'cold backup' in database terminology? — A backup taken when the database is shut down and offline
3. What is a 'log file' in the context of database recovery? — A record of all database activities and changes
4. Which of the following best describes a 'transaction' in a database system from a recovery perspective? — A sequence of operations that must be executed atomically (all or nothing).
5. What is the 'Write-Ahead Logging' (WAL) principle in database recovery? — All log records must be written to stable storage before the corresponding data block is written to disk.
6. What is the concept of 'atomicity' in the context of database transactions and recovery? — All parts of a transaction must be executed successfully.
7. What is the fundamental difference between a 'backup' and a 'log file' in recovery management? — All of the above.
8. What is the 'recovery manager' component in a DBMS responsible for? — Ensuring database consistency after failures using logs and backups
9. What is the main advantage of performing incremental or differential backups over full backups? — Faster backup times and less storage space
10. Which type of backup copies only the data that has changed since the last backup? — Incremental Backup
11. A 'differential backup' copies all data that has changed since the last: — Full Backup
12. Which recovery technique involves creating a copy of the database pages before modifying them? — Shadow Paging
13. Which recovery technique is generally considered simpler to implement but can be less efficient for large databases due to the overhead of page copying? — Shadow Paging
14. In the Deferred Update recovery technique, when are the changes to the database actually written? — Only after the transaction commits
15. Which of the following is a common strategy for storing transaction logs? — On a separate, highly reliable storage medium
16. What is the main advantage of using a separate storage system for backups and transaction logs? — Reduced risk of losing backup/log data if the primary storage fails
17. Which of the following is a potential issue with frequent checkpointing? — Slower transaction processing due to I/O overhead
18. What is the main drawback of performing backups too infrequently? — Higher risk of significant data loss
19. What is the role of 'ARIES' (Algorithm for Recovery and Isolation Exploiting Semantics) in database recovery? — It is a sophisticated log-based recovery algorithm that combines undo and redo operations efficiently.
20. What is the main advantage of Shadow Paging over log-based recovery techniques in some scenarios? — It avoids the need for explicit undo operations for transactions that failed before committing.
21. Which of the following is NOT a characteristic of stable storage, which is ideal for storing log files? — It is slow to write to.
22. What is the main challenge in implementing the Shadow Paging technique? — The overhead of creating and managing shadow pages, especially with large databases.
23. If a transaction is aborted before it commits, which recovery operation is performed? — Undo
24. Which recovery technique uses the log file to undo the effects of incomplete transactions and redo the effects of committed transactions? — Immediate Update
25. To restore a database from a full backup and subsequent differential backups, what is the minimum set of backups required? — The full backup and the latest differential backup
26. To restore a database from a full backup and subsequent incremental backups, what is the minimum set of backups required? — The full backup and all incremental backups in order
27. What does Recovery Time Objective (RTO) refer to in disaster recovery planning? — The maximum acceptable time to restore the database after a failure
28. In Shadow Paging, if a system crash occurs during the write of a new page, what is the state of the database after recovery? — The database reverts to the state before the transaction began.
29. Which of the following is a critical factor in determining the frequency of backups? — The acceptable amount of data loss (Recovery Point Objective - RPO)
30. What is the 'restore' process in database management? — The process of copying data from a backup to the database
31. What is 'transaction rollback'? — The process of undoing the changes made by a transaction
32. What is 'transaction commit'? — The process of permanently making a transaction's changes to the database
33. In a system using Immediate Update recovery, if a transaction fails before committing, what must be done? — The transaction's changes must be undone using the log.
34. What is the primary goal of database recovery techniques? — To ensure data consistency and integrity after a failure
35. What is the purpose of a 'checkpoint' in database recovery? — To periodically save the database state and log information to disk
36. What is the primary goal of a 'full backup' strategy? — To ensure that all data is captured in a single backup set for easy restoration
37. What is the role of the 'undo' operation in log-based recovery? — To reverse the effects of transactions that did not commit
38. What is the purpose of 'block-level' recovery? — To recover specific blocks or pages of the database that are corrupted.
39. What is the purpose of archiving transaction logs? — To store historical log data for long-term retention and auditing
40. What is the role of the 'redo' operation in log-based recovery? — To reapply changes from committed transactions that were lost
41. What is the primary purpose of a 'backup' in database management? — To create a copy of the database for disaster recovery or historical purposes
42. In the context of Immediate Update recovery, what is the purpose of the 'undo' list maintained for each transaction? — To store information required to reverse the transaction's effects.
43. What is the role of the 'System Log' (or transaction log) in database recovery? — To record all operations that modify the database state, enabling undo and redo.
44. Why is it important to test the restore process regularly? — To verify that backups are being created correctly and can be used to recover the database
45. Which of the following is NOT a type of database failure that recovery techniques address? — Network latency
46. Which type of failure requires the longest recovery time, assuming all other factors are equal? — Disk failure affecting database files
47. What is the principle of 'durability' in ACID properties, and how do recovery techniques ensure it? — Committed transactions are permanent, even in the face of system failures; recovery techniques ensure this through logging and backups.
48. Consider a scenario where a system crashes after a transaction has committed, but before the changes are written to the main database file on disk. Which recovery operation is essential to ensure data consistency? — Redo
49. Which of the following is a common strategy to ensure that log records are safely stored before data modifications are committed? — Write log to stable storage before writing data to disk.
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