Use the example schema (16.4) on page 703 to design a query for finding the names of all managers (employees with Title = ’manager’) whose salary is more than |S20,000, but assume that there are three warehouses. Also assume that the total number of employees is 100,000, that 5000 of them make over |S20,000, that the total number of managers is 50, and that 90% of the managers make more than |S20,000.

What will be an ideal response?


The best alternative is the one given in the text.
1. At each of the warehouse sites, select all tuples for which the title is manager.
2. Send these tables to the headquarters site. Do the join there, Then send the sames to site A
The number of bytes to be sent is exactly the same as in the text — 1,300 bytes from
all the warehouse sites to the headquarters, plus 675 bytes from the headquarters site
to site A, for a total of 1,975 bytes.

Computer Science & Information Technology

You might also like to view...

A(n) ________ key that is created from naturally occurring data generated outside of a database such as a driver's license number

Fill in the blank(s) with correct word

Computer Science & Information Technology

Google+ is an example of a(n) ________ network

Fill in the blank(s) with correct word

Computer Science & Information Technology

Which of the following is a method for validating on the W3C CSS validation page?

A. Set location B. By file upload C. Enter URL D. CSS value set

Computer Science & Information Technology

____ view simulates the way a document will look when it is viewed as a Web page.

A. Outline B. Draft C. Print Layout D. Web Layout

Computer Science & Information Technology