Suppose you are given a relation r(a, b, c).a. Give an example of a situation under which the performance ofequality selection queries on attribute a can be greatly affected byhow r is clustered.b. Suppose you also had range selection queries on attribute b. Canyou cluster r in such a way that the equality selection queries onr.a and the range selection queries on r.b can both be answeredefficiently? Explain your answer.c. If clustering as above is not possible, suggest how both typesof queries can be executed efficiently by choosing appropriateindices.

a) The relation r is clustered by the attribute a in below case, Consider that the relation r is…

Answered: Suppose you are given a relation r(a,…

Computer Networking: A Top-Down Approach (7th Edition)

7th Edition

ISBN:9780133594140

Author:James Kurose, Keith Ross

Publisher:James Kurose, Keith Ross

Chapter1: Computer Networks And The Internet

Section: Chapter Questions

Problem R1RQ: What is the difference between a host and an end system? List several different types of end...

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Similar questions

Consider that the normalised training set below is part of a K-Nearest Neighbour “model”:@relation ‘dummy-data-set’@attribute input1 numeric@attribute input2 {a,b,c}@attribute output numeric@data0.5, a, 100, c, 151, b, 20Assume that the input attributes are the first and the second attributes of the training set. What outputvalue would a 3-nearest neighbour (K=3) algorithm predict for an instance with normalised inputattributes (1.0, a)? Explain the results.
Suppose two relationsr and s have histograms on attributes r.A and s.A, respectively, but with different ranges. Suggest how to use the histograms to estimate the size of r ⋈ s. Hint: Split the ranges of each histogram further.
Suppose relation R(a,b,c) has the following tuples: (1,1,3), (1,2,3), (2,1,4), (2,3,5), (2,4,1), (3,2,4), and (3,3,6). Determine the result of the following query: SELECT V.d, SUM(V.c) FROM (SELECT a+b AS d, R.c FROM R)AS V GROUP BY V.d HAVING COUNT(*) 1; Which of the following tuples is in the result set? O a. (3, 12) O b. (3, 6) O c. (5, 7) O d. (6, 7)
For each of the following relations, determine whether the relation is: • Transitive. • A partial order. • A strict order. • An equivalence relation. Reflexive. Anti-reflexive. Symmetric. • Anti-symmetric. Justify all your answers. a. Ris a relation on the set of all people such that (a, b) e R if and only if a and b have a common grandparent. b. Ris a relation on Z such that (x, y) E R if and only if |x – y| < 2. c. Ris a relation on Z* such that (x, y) E R if and only if x is divisible by y. Hint: An integer x is divisible by an integer y with y # 0 if and only if there exists an integer k such that x = yk. d. Ris a relation on Z* such that (x, y) E R if and only if there is a positive integer n such that x" = y. e. Ris a relation on Z x Z such that ((a, b), (c, d)) E R if and only if a < c and b < d.
1. Consider a relation schema R1(A, B, C, D) that satisfies the set of functional dependencies F1 ={A→B, B→C, C→A}.a) Calculate A + and (AC)+b) Can AB→ C? Justify your answer.c) Find all the candidate keys of R1 using F1 and show your steps to find them. 2. Consider a relation schema R2(A, B, C, D) that satisfies the set of functional dependencies F2 = {A→B, C→D, D→AC}.a) Is (AD) is candidate key of R2? Justify your answer.b) Is R2 in BCNF? Explain the reason to your answer.c) If R2 is not in BCNF, give a lossless-join BCNF decomposition of R2. Is this decomposition dependency preserving? 3. Consider a relation schema R3(A, B, C, D, E) that satisfies the set of functional dependencies F3 = {A → BC, AC → BD}.a) Calculate (AC)+ and (AE)+b) Is AB → C in F3 +? Justify your answer.c) Find the canonical cover Fc of F3.d) Is R3 in 3NF? Explain the reason to your answer. If R3 is not in 3NF, give a lossless-join, dependency preserving 3NF decomposition of R3.

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