UGC NET CSE | December 2006 | Part 2 | Question: 20

Question

Two phase protocol in a database management system is :

• A. a concurrency mechanism that is not deadlock free

• B. a recovery protocol used for restoring a database after a crash

• C. Any update to the system log done in 2-phases

• D. not effective in Database

Comments

option A  2 Phase Locking protocol  is popular concurrency protocol which ensures serializability but  can also suffer from deadlock.

Answer 1

option B . As 2 PL is not deadlock free but recoverable.

Comments

2 Phase Protocol may or may not be recoverable because protocol don’t say about commit orders.