Recovery techniques (log-based, shadow paging) MCQs in DBMS
By: Prof. Dr. Fazal Rehman | Last updated: September 23, 2024
What is the primary purpose of log-based recovery techniques in DBMS?
a) To improve query performance
b) To ensure data integrity by recording changes and enabling recovery
c) To reduce the size of the database
d) To manage user access controlAnswer: b) To ensure data integrity by recording changes and enabling recovery
Which recovery technique involves maintaining a log of all operations performed on the database to enable rollbacks and recoveries?
a) Shadow Paging
b) Log-based Recovery
c) Checkpointing
d) SnapshotsAnswer: b) Log-based Recovery
In log-based recovery, what is the primary function of the ‘redo’ log?
a) To undo changes made by a transaction
b) To record changes made by committed transactions
c) To capture the initial state of the database
d) To save the database schemaAnswer: b) To record changes made by committed transactions
Which log-based recovery technique records all changes made by transactions in a sequential log file?
a) Write-Ahead Logging (WAL)
b) Shadow Paging
c) Deferred Update
d) Immediate UpdateAnswer: a) Write-Ahead Logging (WAL)
In which recovery technique are changes applied directly to the database and logged simultaneously?
a) Shadow Paging
b) Deferred Update
c) Immediate Update
d) Undo LoggingAnswer: c) Immediate Update
What is the main advantage of shadow paging over log-based recovery?
a) It requires less storage space for backup
b) It allows for more efficient recovery without logging all operations
c) It is simpler to implement compared to log-based recovery
d) It provides point-in-time recoveryAnswer: b) It allows for more efficient recovery without logging all operations
In shadow paging, what is the role of the ‘shadow page’?
a) To record all changes made to the database
b) To store the previous state of the database for recovery purposes
c) To maintain a record of committed transactions
d) To handle the undo operationsAnswer: b) To store the previous state of the database for recovery purposes
Which recovery technique involves maintaining two page tables, where the shadow page table holds the original state and the current page table holds the latest state?
a) Write-Ahead Logging (WAL)
b) Shadow Paging
c) Deferred Update
d) Log-Based RecoveryAnswer: b) Shadow Paging
What is the primary disadvantage of shadow paging compared to log-based recovery?
a) Higher complexity in recovery operations
b) Increased disk space requirements
c) Slower recovery time
d) Reduced flexibility in recovery optionsAnswer: b) Increased disk space requirements
In log-based recovery, what does the term ‘checkpoint’ refer to?
a) A process of creating a backup of the database
b) A point where the state of the database is recorded to facilitate faster recovery
c) A method for validating transactions
d) A process of logging all transactions for recoveryAnswer: b) A point where the state of the database is recorded to facilitate faster recovery
Which recovery method involves deferring the updates of a transaction until it has been committed?
a) Immediate Update
b) Deferred Update
c) Write-Ahead Logging
d) Shadow PagingAnswer: b) Deferred Update
What is the main benefit of using deferred update in transaction recovery?
a) Immediate application of changes to the database
b) Reduced logging overhead
c) Ability to roll back transactions without affecting the database
d) Improved performance in high-concurrency environmentsAnswer: c) Ability to roll back transactions without affecting the database
In which recovery method are all changes written to the log before they are applied to the database?
a) Shadow Paging
b) Write-Ahead Logging
c) Deferred Update
d) Immediate UpdateAnswer: b) Write-Ahead Logging
How does shadow paging handle a transaction rollback?
a) By restoring the database from the shadow page table
b) By applying undo logs from the transaction log
c) By reloading the last full backup
d) By using deferred updatesAnswer: a) By restoring the database from the shadow page table
Which recovery technique typically requires the database to be in a consistent state before the recovery process can start?
a) Log-Based Recovery
b) Shadow Paging
c) Checkpointing
d) Deferred UpdateAnswer: c) Checkpointing
