For each of the following locking protocols, assuming that every transaction fol

Question

For each of the following locking protocols, assuming that every transaction follows that locking protocol, state which of these desirable properties are ensured: (1) recoverability, (2) avoidance of cascading rollbacks, (3) strict schedules, (4) conflict-serializability, You don’t have to give any explanations, just state for each of (1),(2),(3), (4) YES or NO. For example, your answer might be (1) YES, (2) NO (3) NO (4) YES.

(a) Always obtain an exclusive lock before writing; hold exclusive locks until end-of transaction. No shared locks are ever obtained i.e. don’t need to get locks to read. (b) Always obtain an exclusive lock before writing; hold exclusive locks until end-of transaction. In addition, obtain a shared lock before reading; shared locks can be released at any time.

(c) Always obtain an exclusive lock before writing; hold exclusive locks until end-of transaction. In addition, obtain a shared lock before reading; shared locks can be released at any time. In addition, locking is two-phase.

Explanation / Answer

Answer)

This locking mechanism depends on ACID Property.

The properties which are ensured are as follows:

ACID: Atomicity, Consistency, Durability, and Isolation.

1) Yes,

2) No

3) Yes

4) Yes,

a) True.

b) True. The shared lock can be released anytime

c) Yes Locking mechanism is 2 phased (2PL) which is concurrency control methods which help to guarantee the serializable.

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