Each transaction begins at the time slot of its first Read and commits right after its last Write (same time slot). 

Regarding the following questions, give and justify your answers. 

1) Assume a checkpoint is made between t₄ and t₅, what should be done to the four transactions when the crash happens between t₆ and t₇. 

2) Is the transaction schedule conflict serializable? Give the precedence graph to justify your answer. 

3) Give a serial schedule of these four transactions.) 

4) Construct a schedule (which is different from above) of these four transactions which causes deadlock when using two-phase locking protocol. If no such schedule exists, explain why. 

 

Consider the schedule below. Here, R(*) and W(*) stand for 'Read' and 'Write', respectively. T, T2, T3 and 74 represent four transactions and t, represents a time slot. Time ti t2 13 14 ts t6 t7 t8 to t10 til t12 T R(B) R(A) W(B) W(A) 12 R(A) R(A) R(B) W(B) W(A) T3 R(B) W(B) T4 R(A) W(A) R(B) W(B)