Suppose we have a set of transactions T1, ..., Tn. Each transaction reads the same element X and writes back to X a value that is the result of multiplying X by some constant (eg X = X * 5). Each transaction may have a different constant, and for clarity you can call its constant cn. Now consider a schedule of these transactions, S, which is serializable but not conflict-serializable nor serial. Describe S, and any assumptions you make about X, Tn, or cn. Why is your S serializable? Why is your S not conflict-serializable?
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Now, let's consider a schedule S where each transaction Tn reads the value of X and writes back a new value that is the result of multiplying X by a constant Cn. Each transaction Tn has a different constant Cn. For example, let's say we have three transactions Show more…
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Consider the following transactions with data items $P$ and $Q$ initialized to ${ }^{4} 0^{\prime}$ : $T_{1}: \operatorname{read}(P)$ $\operatorname{Read}(Q)$ if $p=0$ then $Q=Q+1$ Write $(Q)$ $T_{2}: \operatorname{read}(Q)$ $\operatorname{Read}(P)$ if $Q=0$ then $p=p+1$ Write $(P)$ Any non-serial interleaving of $T_{1}$ and $T_{2}$ for concurrent execution leads to (A) a serializable schedule (B) a schedule that is not conflict serializable (C) a conflict serializable schedule (D) a schedule for which a precedence graph cannot be drawn
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Consider schedule $S_{3}$, which is a combination of transactions $T_{1}, T_{2}$ and $T_{3}$ from Q. No.11. $S_{3}: r_{1}(x), r_{2}(z), r_{1}(z), r_{3}(x), r_{3}(y), w_{1}(x), c_{1}, w_{3}(y), c_{3}$ $r_{2}(y), w_{2}(z), w_{2}(v), c_{2} ?$ Which of the following is true? (A) Recoverable and conflict serializable (B) Recoverable but not conflict serializable (C) Conflict serializable but not Recoverable (D) Not recoverable and not conflict serializable
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