Database 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), con

ict-serializability, (2) recoverability, (3)

avoidance of cascading rollbacks, (4) strict schedules. 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-oftransaction. 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-oftransaction. 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-oftransaction. In addition,

obtain a shared lock before reading; shared locks can be released at any time. In addition, locking is

two-phase.