Skip to content
Related Articles
Open in App
Not now

Related Articles

ISRO | ISRO CS 2015 | Question 17

Improve Article
Save Article
  • Last Updated : 03 Apr, 2018
Improve Article
Save Article

Consider the following log sequence of two transactions on a bank account, with initial balance 12000, that transfer 2000 to a mortgage payment and then apply a 5% interest.
1. T1 start
2. T1 B old=1200 new=10000
3. T1 M old=0 new=2000
4. T1 commit
5. T2 start
6. T2 B old=10000 new=10500
7. T2 commit
Suppose the database system crashes just before log record 7 is written. When the system is restarted, which one statement is true of the recovery procedure?
(A) We must redo log record 6 to set B to 10500
(B) We must undo log record 6 to set B to 10000 and then redo log records 2 and 3
(C) We need not redo log records 2 and 3 because transaction T1 has committed
(D) We can apply redo and undo operations in arbitrary order because they are idempotent.

Answer: (B)


Quiz of this Question
Please comment below if you find anything wrong in the above post

My Personal Notes arrow_drop_up
Related Articles

Start Your Coding Journey Now!