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.

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.

Database Systems: Design, Implementation, & Management

11th Edition

ISBN:9781285196145

Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Publisher:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Chapter10: Transaction Management And Concurrency Control

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

Consider a federated database system in which it is guaranteed that at most one global transaction is active at any time, and every local site ensures local serializability.a. Suggest ways in which the federated database system can ensure thatthere is at most one active global transaction at any time.b. Show by example that it is possible for a nonserializable global scheduleto result despite the assumptions.
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 multi-user database system is used to support the customer payment operations of a XYZ store. Unfortunately, the system currently does not enforce concurrent control on transactions accessing and updating the data. A particular customer had a balance due of HK$ 300 when the following three transactions related to the customer were processed at the same time: (i) Payment of HK$ 300; (ii) Purchase on credit of HK$ 150; and (iii) Merchandise return (credit) of HK$ 100. Each of the three transactions read the customer record when the balance was HK$ 300. That is, all transactions have read the record before any of them was completed. The updated customer record was returned from the transactions to the database in the order of first (i), then (ii) and finally (iii). (a) After the last transaction was completed, what balance will be recorded for the customer? (b) What balance should be actually recorded for the customer after the three transactions have been processed?
Computer Science Propose a relation schema for storing the access rights associated with user groups in a distributed database catalog, and give a fragmentation scheme for that relation, assuming that all members of a group are at the same site.
2. For a transaction database such as follows, there exists a hierarchy on categories of items: TID Items apple, lamb, rice apple, sugar, rice beef, rice, apple apple, pear, sugar rice 100 200 Fruit Food 300 аpple рear meat rice sugar 400 500 lamb beef apple, pear beef, rice 600 700 (a) Find all frequent itemsets using the basic algorithm given in the lecture (minimum support = 3 transactions). (b) Generate all generalised association rules (minimum confidence = 90%)
Consider a database that has the relation schema (EmpId, EmpName, and DeptName). An instance of the schema EMP and a SQL query on EMP it are given below. EMP Empld EmpName DeptName 1 XYA AA ХҮВ AA ХҮС AA SELECT AVG(EC. Num) 4. XYD AA FROM EC XYE AB WHERE (DeptName, Num)IN (SELECT DeptName, COUNT(Empld) AS XYF АВ XYG ХҮН AB EC(DeptName, Num) 8 AC FROM EMP XYI AC GROUP BY DeptName) 10 XYJ AC 11 XYK AD 12 XYL AD 13 ΧΥΜ AE The output of executing the SQL query is
Consider a federated database system in which every local site ensures local serializability, and all global transactions are read only. a. Show by example that nonserializable executions may result in such a system. b. Show how you could use a ticket scheme to ensure global serializability.
Consider a database system that includes an atomic increment operation, inaddition to the read and write operations. Let V be the value of data item X.The operationincrement(X) by C sets the value of X to V + C in an atomic step. The value of X is not availableto the transaction unless the latter executes a read(X).Assume that increment operations lock the item in increment mode using thecompatibility matrix in Figure 18.25.a. Show that, if all transactions lock the data that they access in the correspondingmode, then two-phase locking ensures serializability.b. Show that the inclusion of increment mode locks allows for increasedconcurrency.
Consider a relation R(a, b, c, d) containing 1 million records, where each page of the relation holds 10 records. R is organized as a heap file with unclustered indexes, and the records in R are randomly ordered. Assume that attribute a is a candidate key for R, with values lying in the range 0 to 999,999. For each of the following queries, name the approach that would most likely require the fewest I/Os for processing the query. The approaches to consider follow: ■ Scanning through the whole heap file for R. Using a B+ tree index on attribute R.a. Using a hash index on attribute R.a. The queries are: 1. Find all R tuples. 2. Find all R tuples such that a 50 and a < 100.
Consider the relation schema R=VWXYZ, with the set of functional dependencies F = {VW->XY, V->X, W->Z, YZ→Z, Z->V} А. Give three independent reasons why the following table cannot possibly be a legal instance of R. V W Z yl x2 X Y v1 w1 х1 z1 _y2 x1 v2 w1 z1 v2 w2 y2 z2
Consider the relation schema R=VWXYZ, with the set of functional dependencies F = {VW->XY, V>X, W->Z, YZ->Z, Z→V} A. Give three independent reasons why the following table cannot possibly be a legal instance of R. V W X Y v1 w1 х1 yl z1 v2 w1 x2 y2 z1 v2 w2 x1 y2 z2 B. Show the functional dependencies that hold on each of R1=VWX and R2=WYZ. You do not need to show trivial functional dependencies, or those implied by others in the same set, but you must show all others. C. Is the decomposition of R into R1=VWX and R2=WYZ lossless-join? Why or why not?
Consider a database for a bank where the database system uses snapshot isolation.Describe a particular scenario in which a nonserializable execution occursthat would present a problem for the bank.

SEE MORE QUESTIONS

Recommended textbooks for you

Database Systems: Design, Implementation, & Manag…

Computer Science

ISBN:

9781285196145

Author:

Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Publisher:

Cengage Learning