Transaction ,concurrency control, serializable DBMS question


#1

Consider the following schedule:
R1(A),R2(A),W2(A),commit2,W1(A),commit1

a) not conflict serializable.

b) conflict serializable T2 => T1

b) conflict serializable T1 => T2

d)conflict serializable to both T2 => T1,T1 => T2


#2

The given schedule is:
R1(A),R2(A),W2(A),commit2,W1(A),commit1

We have T1=>
R1(A),W1(A)

We have T2=>
R2(A),W2(A)

The only non -conflicting pair of operation we have is R1(A),R2(A)
Lets try to swap these two opearations:
The new schedule will be:
R2(A),R1(A),W2(A),commit2,W1(A),commit1

This is not either T1=>T2 or T2=>T1,
so option a is correct,the given schedule is not conflict serializable.

Bonus:What is view serializable.A schedule is conflict serializable ,is it guaranteed that its view serializable too.What about the reverse?.Give supportive examples in your answer.