Chapter 17: Problem 2
Discuss the different types of failures. What is meant by catastrophic failure?
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Chapter 17: Problem 2
Discuss the different types of failures. What is meant by catastrophic failure?
These are the key concepts you need to understand to accurately answer the question.
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Get started for freeConsider the three transactions \(T_{1}, T_{2},\) and \(T_{3},\) and the schedules \(S_{1}\) and \(S_{2}\) given below. Draw the serializability (precedence) graphs for \(S_{1}\) and \(S_{2},\) and state whether each schedule is serializable or not. If a schedule is serializable, write down the equivalent serial schedule(s). $$\begin{array}{l} T_{1}: r_{1}(X) ; r_{1}(Z) ; w_{1}(X) \\ T_{2}: r_{2}(Z) ; r_{2}(Y) ; w_{2}(Z) ; w_{2}(Y) \\ T_{3}: r_{3}(X) ; r_{3}(Y) ; w_{3}(Y) ; \\ S_{1}: r_{1}(X) ; r_{2}(Z) ; r_{1}(Z) ; r_{3}(X) ; r_{3}(Y) ; w_{1}(X) ; w_{3}(Y) ; r_{2}(Y) ; w_{2}(Z) ; w_{2}(Y) \\ S_{2}: r_{1}(X) ; r_{2}(Z) ; r_{3}(X) ; r_{1}(Z) ; r_{2}(Y) ; r_{3}(Y) ; w_{1}(X) ; w_{2}(Z) ; w_{3}(Y) ; w_{2}(Y) \end{array}$$
Why is an explicit transaction end statement needed in SQL but not an explicit begin statement?
Consider schedules \(S_{3}, S_{4},\) and \(S_{5}\) below. Determine whether each schedule is strict, cascadeless, recoverable, or nonrecoverable. (Determine the strictest recoverability condition that each schedule satisfies.) $$\begin{array}{l} S_{3}: r_{1}(X) ; r_{2}(Z) ; r_{1}(Z) ; r_{3}(X) ; r_{3}(Y) ; w_{1}(X) ; c_{1} ; w_{3}(Y) ; c_{3} ; r_{2}(Y) ; w_{2}(Z) ; w_{2}(Y) ; c_{2} \\ S_{4}: r_{1}(X) ; r_{2}(Z) ; r_{1}(Z) ; r_{3}(X) ; r_{3}(Y) ; w_{1}(X) ; w_{3}(Y) ; r_{2}(Y) ; w_{2}(Z) ; w_{2}(Y) ; c_{1} ; c_{2} ; c_{3} \\ S_{5}: r_{1}(X) ; r_{2}(Z) ; r_{3}(X) ; r_{1}(Z) ; r_{2}(Y) ; r_{3}(Y) ; w_{1}(X) ; c_{1} ; w_{2}(Z) ; w_{3}(Y) ; w_{2}(Y) ; c_{3} ; c_{2} \end{array}$$
Describe situations where each of the different isolation levels would be useful for transaction processing.
Define the violations caused by each of the following: dirty read, nonrepeatable read, and phantoms.
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