Question 8153 – Transactions

Consider the following database schedule with two transactions, T₁ and T₂.
S = r₂(X); r₁(X); r₂(Y); w₁(X); r₁(Y); w₂(X); a₁; a₂
where r_i(Z) denotes a read operation by transaction T_i on a variable Z, w_i(Z) denotes a write operation by T_i on a variable Z and a_i denotes an abort by transaction T_i.
Which one of the following statements about the above schedule is TRUE?

Correct Answer: C

Given schedule is,

Now let’s check statements one by one,
A) False, because there is no dirty read. So, it is recoverable.
B) False, because there is to dirty read. So, no cascading aborts.
C) True.
D) False, because there is Transaction T₂ which written the value of x which is written by T₁ before T₁ has aborted. So, not strict.