Suppose that you are running manually the Apriori algorithm to find the frequent itemsets in a given transaction database. Currently, you have determined the candidate set of 2-itemsets, C2, and the corresponding support count of each candidate 2-itemset. Assuming that the minimum support count is 3, which candidate 2-itemsets in C₂ would be frequent 2- itemsets? Select all that apply. {I₁, I2}, support count = 1 {I1, I3), support count = 3 {I1, I4}, support count = 3 {I2, I3), support count = 2 {I2, I4}, support count = 1 {I3, I4}, support count = 4

Suppose that you are running manually the Apriori algorithm to find the frequent itemsets in a given transaction database. Currently, you have determined the candidate set of 2-itemsets, C2, and the corresponding support count of each candidate 2-itemset. Assuming that the minimum support count is 3, which candidate 2-itemsets in C₂ would be frequent 2- itemsets? Select all that apply. {I₁, I2}, support count = 1 {I1, I3), support count = 3 {I1, I4}, support count = 3 {I2, I3), support count = 2 {I2, I4}, support count = 1 {I3, I4}, support count = 4

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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We are given the following transaction schedule, where A,B,C are the addresses of the records in the database and T1 and T2 are the transactions. T1 R(A) W(A) R(B) W(B) R(C) W(C) COMMIT T2 R(C) R(B) W(B) a) Show that using strict two-phase locking leads to complications b) For example a, draw a »waits-for<< graph c) Resolve the problems in example a, using the "Wound-Wait" protocol R(A) W(A) W(C) COMMIT
Consider a database with objects A, B, X and Y. Assume that there are two transactions T1 and T2 performing R (read) and W (write) operations before they C (commit). Given are two example schedules. Identify them as serializable or not serializable. Also explain with reason(s). If any of the schedule(s) is identified as not serializable then show with proof that strict 2PL disallows this schedule. [6] a) RI[A] → W1[A] → R2[B] → W2[B] → R2[A] → W2[A] → RI[C] → W1[C] →C1 + C2 b) R1[X]→R1[Y] → R2[X] →W2[X] → R2[Y]→W1[X] → W1[Y] → W2[Y] →C1 C2
A transaction database contains ten transactions shown below and minimum_support = 30%. Using A-priori, find all frequent itemsets that contain item i. How many frequent itemsets that contain i do we have? TID Items bought { s, u, s, a, n} { s, a, r, a} { s, a, m} 1 2 3 {r, i, c, h, a, r, d} {e,r, i, c} {n, i, c, k} {p, a, t, r, i, c, k} {e, m, i, 1, y} {c,h, a, r, l, e, s} 6. 7 8 9. 10 [lidal
Suppose that the transactions at a fast-food restaurant during one afternoon are {hamburger, fries, regular soda}, {cheeseburger, fries, regular soda}, {apple, hamburger, fries, regular soda}, {salad, diet soda}, {hamburger, onion rings, regular soda}, {cheeseburger, fries, onion rings, regular soda}, {hamburger, fries}, {hamburger, fries, regular soda}. Find the count and support of {cheeseburger}.
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: . Suppose that a large store has a transactional database that is distributed among four locations. Transactions in each component database have the same format, namely Tj {₁,..., im}, where Tj is a transaction identifier, and ik (1 ≤ k ≤ m) is the identifier of an item purchased in the transaction. Propose an efficient algorithm to mine global association rules. You may present your algorithm in the form of an outline. Your algorithm should not require shipping all of the data to one site and should not cause excessive network communication overhead.
a. Which itemsets (of any length) are frequent if you know that {ace} and {ad} are the only maximal frequent itemsets? b. If all transactions that contain {bcd} also contain {def}, which of the following itemsets {bcd}, {def}, {bcde}, {bcdf}, {bcdef} are not closed?
Consider a database with objects X and Y and assume that there are two transactions T1 and T2. Transaction T1 reads objects X and Y and then writes object X. Transaction T2 reads objects X and Y and then writes objects X and Y. 1. Give an example schedule with actions of transactions T1 and T2 on objects X and Y that results in a write-read conflict. 2. Give an example schedule with actions of transactions T1 and T2 on objects X and Y that results in a read-write conflict. 3. Give an example schedule with actions of transactions T1 and T2 on objects X and Y that results in a write-write conflict.
Let D be a database of the patients with only two columns. The dataset has been encrypted as follows: 1. Column 1 contains patient ids are unique in the entire column. 2. Column 2 contains the disease name. A disease name can appear in multiple rows. In other words, two or more patients can have the same disease. The above database is secured using the technique of accumulating automata (i.e., the technique for searching over secret shared datasets) We are allowed to execute only some fixed (say 10) queries over this table and all such queries are for fetch operation. In other words, we are allowed to execute only 10 selection queries on this table. This question has two parts, as follows: a. Does the above-mentioned scheme is IND-CKA1 secure. b. Justify your answer. a. If you think that the scheme is IND-CKA1 secure, prove this. OR b. If you think that the scheme is not IND-CKA1 secure, prove this.
1 43 1112 41 42 32 Example Output 4 2
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Consider a database with objects X and Y. There are two transactions, as follows: T1: read(X), write(Y), write(X), commit T2: read(Y), write(X), write(Y), commit Give an example schedule that results in a Read-Write (RW) conflict. Explain why Strict Two-Phase Locking (Strict 2PL) would not allow your schedule from part (a) above. Give an example schedule that results in a Write-Write (WW) conflict. Explain why Strict Two-Phase Locking (Strict 2PL) would not allow your schedule from part (c) above.