Name_________________________________
Section You Usually Attend________________
UNIVERSITY OF CALIFORNIA
College of Engineering
Department of EECS, Computer Science Division
Midterm Exam: Introduction to Database Systems
This exam has four problems, each worth 25 points. There is also 10 points of extra credit available. Each
problem is made up of multiple questions. You should read through the exam quickly and plan your
time-management accordingly. Before beginning to answer a question, be sure to read it carefully and to
answer all parts of every question!
You must write your answers on the answer sheets provided. You may use the sheets with questions as
scratch paper. You also must write your name at the top of every page, and you must turn in all the pages
of the exam. Do not remove pages from the stapled exam! Two pages of extra answer space have been
provided at the back in case you run out of space while answering. If you run out of space, be sure to make a
"forward reference" to the page number where your answer continues.
Good luck!
1. Sorting [25 points]
To receive full credit for this problem you must write down relevant formulas and show your work.
We are trying to sort a file containing 250,000 blocks with only 250 buffers available in the buffer pool for
sorting. The file contains fixed length tuples.
a) [5 points] How many initial runs will be generated if quicksort is used to sort tuples in
memory?
b) [5 points] How many total I/O will the sort perform, including the cost of writing out the
output?
In the following questions, assume that the average time to locate a random block (seek and rotational delay)
takes 10 ms, while the time to transfer a block takes 5 ms.
c) [5 points] During our sort, if we merge runs a block at a time (in memory we set aside one
buffer frame per input run for merging) what percent of the total disk bandwidth are we
utilizing?
d) [5 points] Suppose we want to achieve a disk bandwidth utilization of 90%. How many
buffer frames per run should we set aside in our buffer pool?
e) [5 points] What is the tradeoff in setting aside aside more buffer frames (i.e. higher disk
bandwidth utilization) per run?
2. Indexes [25 points]
CS 186, Midterm #1 Fall 1998
Name_________________________________ Section You Usually Attend________________exam #professor (e.g., Professor J. Wawrzynek)1
