Data Mgmt Lab_Part_42 - 124 Chapter 12 (a)...

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124 Chapter 12 (a) σ Sailors.sid< 50 , 000 ( Sailors ) (b) σ Sailors.sid =50 , 000 ( ) 2. A hash index on the search key h Sailors.sid i . (a) σ Sailors.sid< 50 , 000 ( ) (b) σ Sailors.sid =50 , 000 ( ) 3. A B+-tree index on the search key h Sailors.sid, Sailors.age i . (a) σ Sailors.sid< 50 , 000 Sailors.age =21 ( ) (b) σ Sailors.sid =50 , 000 Sailors.age> 21 ( ) (c) σ Sailors.sid =50 , 000 ( ) (d) σ Sailors.age =21 ( ) 4. A hash-tree index on the search key h Sailors.sid, Sailors.age i . (a) σ Sailors.sid =50 , 000 Sailors.age =21 ( ) (b) σ Sailors.sid =50 , 000 Sailors.age> 21 ( ) (c) σ Sailors.sid =50 , 000 ( ) (d) σ Sailors.age =21 ( ) Answer 12.4 Answer omitted. Exercise 12.5 Consider again the schema with the Sailors relation: Sailors( sid: integer , sname: string , rating: integer , age: real ) Assume that each tuple of Sailors is 50 bytes long, that a page can hold 80 Sailors tuples, and that we have 500 pages of such tuples. For each of the following selection conditions, estimate the number of pages retrieved, given the catalog information in the question. 1. Assume that we have a B+-tree index T on the search key h Sailors.sid i ,andas- sume that IHeight ( T )=4, INPages ( T ) = 50, Low ( T ) = 1, and High ( T ) = 100,000.
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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.

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Data Mgmt Lab_Part_42 - 124 Chapter 12 (a)...

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