Project ForgeDatabase Management Systems
SQL & Transactions
GATE 2010
Medium
Which of the following concurrency control protocols ensure both conflict serializability and freedom from deadlock? I. 2-phase locking II. Time-stamp ordering
- AI only
- II only
- CBoth I and II
- DNeither I nor II
Explanation
2-phase locking guarantees conflict serializability but can still deadlock (transactions can mutually wait on each other's locks). Timestamp ordering guarantees serializability AND is inherently deadlock-free (transactions abort instead of waiting, so no circular wait can form). Only II satisfies both.
Source: GATE CS 2010 (2010)
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