15 Questions
What is the purpose of taking three or four checkpoints an hour in a database system?
To reduce the recovery time needed in case of failure.
Why is it recommended to store the log file on a separate disk from the main database files?
To lower the risk of both database files and log file being damaged simultaneously.
In case of extensive damage to a database due to a disk head crash, what is the primary step needed for recovery?
Restore the last backup copy of the database on a replacement disk.
What action is necessary if a database becomes inconsistent due to a system crash during transaction execution?
Undo the changes that caused inconsistency and redo necessary transactions.
What does the recovery procedure involve when a database has not been physically damaged?
Reapplying the update operations on committed transactions using the log file.
In the context of deadlock prevention, what is the primary action taken if a lock request times out?
The DBMS assumes deadlock and aborts then restarts the transaction.
What solution is used by several commercial DBMSs for deadlock prevention if a lock request times out?
Assuming deadlock and aborting then restarting the transaction.
Which of the following algorithms allows only older transactions to wait for younger ones in case of a lock request conflict?
Wait-Die
What is the symmetrical approach used in the Wound-Wait algorithm for resolving lock request conflicts?
Only younger transactions can wait for older ones.
Which variant of the Two-Phase Locking protocol ensures that transactions obtain all their locks at the beginning or wait until all the locks are available?
Conservative 2PL
'Wound-Wait' and 'Wait-Die' algorithms were proposed by which researchers?
Rosenkrantz et al.
'Conservative 2PL' differs from 'Basic 2PL' by:
Ensuring all locks are obtained at the start of a transaction.
'Livelock' in transactions can occur when:
'Conservative 2PL' is implemented without proper timeout mechanisms.
'Extensive damage caused by disk head crash' is an issue related to:
'Two-phase locking protocol.'
What is the primary aim of using 'symmetrical approaches' in algorithms like 'Wound-Wait?'
To ensure equal treatment between younger and older transactions.
Test your knowledge on database transaction problems such as lost update and uncommitted dependency. Learn how to prevent issues like lost updates and dirty reads in transactions. Figure out solutions to ensure data consistency in databases.
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