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Unformatted text preview: 148 Chapter 15 (b) Suppose that a clustered B+ tree index on dname is (the only index) avail able. What is the cost of the best plan? (c) Suppose that a clustered B+ tree index on h title, dname i is (the only index) available. What is the cost of the best plan? (d) Suppose that a clustered B+ tree index on h title, ename i is (the only index) available. What is the cost of the best plan? (e) Suppose that a clustered B+ tree index on h dname, title, ename i is (the only index) available. What is the cost of the best plan? (f) Suppose that a clustered B+ tree index on h ename, title, dname i is (the only index) available. What is the cost of the best plan? 3. Suppose that the query is as follows: SELECT E.title, COUNT (*) FROM Executives E GROUP BY E.title (a) Suppose that a clustered B+ tree index on title is (the only index) available. What is the cost of the best plan? (b) Suppose that an unclustered B+ tree index on title is (the only index) avail able. What is the cost of the best plan? (c) Suppose that a clustered B+ tree index on ename is (the only index) available. What is the cost of the best plan? (d) Suppose that a clustered B+ tree index on h ename, title i is (the only index) available. What is the cost of the best plan? (e) Suppose that a clustered B+ tree index on h title, ename i is (the only index) available. What is the cost of the best plan? 4. Suppose that the query is as follows: SELECT E.title, COUNT (*) FROM Executives E WHERE E.dname > W% GROUP BY E.title Assume that only 10% of Executives tuples meet the selection condition....
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This note was uploaded on 01/17/2012 for the course EGN 4302 taught by Professor Dr.vishak during the Fall '12 term at University of Central Florida.
 Fall '12
 Dr.Vishak

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