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Subject: Database Management Systems (CO3021)
Semester 1, 2020-2021
Chapter 5: Introduction to Transaction Processing Concepts and Theory
Question 5.1. Differentiate multiuser systems from single-user systems. Give their examples.
Question 5.2. Describe different types of failures and give their examples.
Question 5.3. What is a transaction? Give 3 examples.
Question 5.4. Discuss the ACID properties of a transaction.
Question 5.5. What is a system log? What records are stored in the log? Write the content of the log for
your transactions in Question 5.3.
Question 5.6. What is a commit point? Give an example.
Question 5.7. What is a schedule? Give an example.
Question 5.8. Given the following transactions:
T1: r1(X); r1(Z); w1(X); c1;
T2: r2(Z); r2(Y); w2(Z); w2(Y); c2;
T3: r3(X); r3(Y); w3(Y); c3;
What are valid schedules? Write their log contents.
S1: r1(X); r1(Z); r3(X); r3(Y); w1(X); w3(Y); c1; c3;
S2: r2(Z); r3(X); r2(Y); r3(Y); w2(Z); w3(Y); w2(Y); a3; c2;
S3: r2(Z); r1(X); r1(Z); w2(Z); w1(X); r2(Y); w2(Y); c2; c1;
S4: r1(X); r3(Y); r1(Z); w3(Y); w1(X); c1; r3(X); c3;
Question 5.9. What are recoverable schedules? What are cascadeless schedules? What are strict
schedules?
Question 5.10. What is the recoverability characteristic of each following schedule?
S5: r1(X); r2(Z); r1(Z); r3(X); r3(Y); w1(X); c1; w3(Y); c3; r2(Y); w2(Z); w2(Y); c2;
S6: r1(X); r2(Z); r1(Z); r3(X); r3(Y); w1(X); w3(Y); r2(Y); w2(Z); w2(Y); c1; c2; c3;
S7: r1(X); r2(Z); r3(X); r1(Z); r2(Y); r3(Y); w1(X); c1; w2(Z); w3(Y); w2(Y); c3; c2;
S8: r1(A); r2(B); w1(B); c1; w2(C); c2; r3(B); r3(C); w3(D); c3;
S9: r1(A); w1(B); c1; r2(B); w2(C); c2; r3(C); w3(D); c3;
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