Two concurrent executing transactions 1 and T 2 are allowed to update same stock item say ' A ' in an uncontrolled manner. In such scenario, following problems may occur :

(a) Dirty read problem

(b) Lost update problem

(c) Transaction failure

(d) Inconsistent database state Which of the following option is correct if database system has no concurrency module and allows concurrent execution of above two transactions?

1. A(a), (b) and (c) only
2. B(c) and (d) only
3. C(a) and (b) only
4. D(a), (b) and (d) only

Pick an option to check yourself, or open the answer below.

Show answer & explanation

Correct answer: D. (a), (b) and (d) only

Explanation

Without concurrency control, dirty reads, lost updates and an inconsistent database can occur. Transaction failure is not caused by interleaving itself.