{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Data Mgmt Lab_Part_42

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

This preview shows pages 1–2. Sign up to view the full content.

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.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 3

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

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online