Gate2017 cs Q53

53In a database system, unique time stamps are assigned to each transaction using Lamport’s logical clock. Let TS(T₁) and TS(T₂) be the timestamps of transactions T₁ and T₂ respectively. Besides, T₁ holds a lock on the resource R, and T₂ has requested a conflicting lock on the same resource R. The following algorithm is used to prevent deadlocks in the database system assuming that a killed transaction is restarted with the same timestamp.
if TS(T₂) < TS(T₁) then
T₁ is killed
else T₂ waits.
Assume any transactions that is not killed terminates eventually. Which of the following is TRUE about the database system that uses the above algorithm to prevent deadlocks?

Option : A
Explanation :
Given,
if TS(T₂) <TS(T₁) then
T₁ is killed
else T₂ waits.
- T₁ holds a lock on the resource R
- T₂ has requested a conflicting lock on the same resource R
According to algo, TS(T₂) <TS(T₁) then T1 is killed else T2 will wait. So in both cases neither deadlock will happen nor starvation.
Therefore, option A is correct

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