[SOLVED] CS考试辅导 Question 1)

Question 1)
Information Management Teacher: Prof.
June 4, 2019
Time available 2:00 hours

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1. Discuss the problem of serializability in a distributed database system.
2. Describe then the concept of logical clock, illustrating its importance, advantages, and disadvantages in distributed
scenarios.
3. Illustrate the working of Lamport clocks.
4. Fill the attached schema indicating the timestamp associated with each operation of each process. For the exercise, assume that all the timestamps are initialized to 0. Operations are denoted with a tick on the line of the corresponding process.
Question 2)
1. Considering a data cube, discuss slice-and-dice, roll-up, and drill-down operations providing also a simple example of each operation.
2. Fill the attached table with the answer to the query that would be computed by a relational system.
Question 3)
1. Describe and discuss the association rule mining and the frequent itemset mining problems.
2. Illustrate the relationship between these two problems.
3. Illustrate the working of FP-trees for solving the frequent itemset mining problem.
4. Considering the table attached and assuming min sup=0.75, identify all the frequent itemsets using FP-trees.
Question 4)
Illustrate and discuss the CAP theorem. Which are the implications of this theorem in practice? Question 5) only for students who did not attend database course with Prof. Samarati
1. IllustrateACIDproperties.
2. Given the following schedule
w3(z) r3(y) w2(z) w2(x) r2(y) r3(x) w1(y) w3(x)w1(z)
tell if it is VSR and/or CSR indicating (when existing) all the equivalent serial schedules.

Matr: Question
Surname, Name:
Final Mark:
Information Management – June 4, 2019

Matr: Surname, Name: Question 1.4

Surname, Name: quantity t-shirt red Milan 100 t-shirt blue Milan 150 t-shirt red Florence 70 t-shirt white Florence 50 pants blue Milan 200 pants blue Florence 80 pants white Milan 20 pants white Florence 30
Question 2.2
select product, color, location, sum(quantity)
where color=”blue” or color=”white”
group by grouping sets ((product,color), (product,city), (product))
Matr: product

Matr: Surname, Name: Question 3.4 TID Items
1 B,D,C,A 2 B,A,E
3 A,D,B,E 4 C,D,A

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