[SOLVED] Question 1)

Question 1)
Information Management Prof.
September 27, 2019
Time available 2:00 hours

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1. Clearly illustrate the concepts of data-centric and client-centric consistency, describing the differences between the two concepts, and clarifying in which scenario each consistency concept can (or should) be adopted.
2. Consider the following schedule of operations performed by four processes over one variable (initially set to zero): P1: R(X =2)R(X =3)R(X =4)
P2: R(X =1)W(X =2)R(X =3)
P3: W (X = 1) W (X = 3) R(X = 2)
P4: R(X =2)R(X =3)W(X =4)
(a) Is the schedule sequential consistent?
If sequential consistency is satisfied, include the minimum number of operations that makes the schedule non sequential consistent.
Otherwise, indicate the minimum number of operations (and which one) that should be removed to guarantee sequential consistency.
(b) Is the schedule causal consistent?
List all the causal dependencies in the schedule.
If the schedule is causal consistent, include the minimum number of operations to make the schedule non causal consistency.
If the schedule is not causal consistent, indicate the operation(s) that should be removed to guarantee causal consistency.
Question 2)
1. Illustrate R-tree indexes for data warehouses, describing the working of search, insert, and delete operations.
2. Considering the attached spatial dataset, illustrate the corresponding R-tree and the working of a search for the values in
the gray rectangle.
Question 3)
1. Illustrate the apriori property for the efficient identification of frequent itemsets.
2. Illustrate how to extract strong association rules from frequent itemsets, also providing an example.
3. Considering the table attached and assuming min sup=0.75, identify all the frequent itemsets using apriori algorithm.
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. Illustrate the write-ahead-log and commit precedence rules for log management.
2. Given the following log:
DUMP, B(T1), I(T1,O1,A1), B(T2), CK(. . . ), U(T2,O2,B2,A2), B(T3), D(T3,O3,B3), U(T1,O4,B4,A4), C(T2), I(T3,O5,A5), B(T4), D(T4,O6,B6), A(T4), CK(. . . ), B(T5), D(T5,O7,B7), C(T1), U(T5,O8,B8,A8), B(T6), C(T5), U(T6,O9,B9,A9), B(T7), A(T6), FAILURE
(a) write, for each checkpoint record, active transactions;
(b) illustrate in the details the steps of a warm restart to recover from failure.

Matr: Question
Surname, Name:
Final Mark:
Information Management September 27, 2019

Matr: Surname, Name: Question 2.2

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