CPS 432/562 Homework #5
Coverage: [DBCB] §18.4-18.6, pp. 940-963 and
§20.1-20.5, pp. 1047-1082
Assigned: March 29
Due: April 10, 4:30p, in class
- (5+5=10 points) Exercise 18.6.1 (only parts b and c) on p. 963 from [DBCB]:
Consider, for variety, an object-oriented database.
The objects of class C are stored on two blocks,
B1 and B2.
Block B1 contains objects O1 and
O2, while block B2 contains
objects O3, O4, and
O5. Class extents, blocks, and objects form a
hierarchy of lockable
database elements. Give the sequence of lock requests and the response
of a warning-protocol-based scheduler
to the following sequences of requests. You may assume all requests
occur just before they are needed, and all unlocks occur at the
end of the transaction.
- r1(O5); w2(O5);
- r1(O1); r1(O3);
- (10 points) Exercise 20.3.2 (only part c) on p. 1070 from [DBCB]:
Consider the following relations:
Computer(number, proc, speed, memory, hd)
Monitors(number, screen, maxResX, maxResY)
Understand that the attribute number of both relations
to refer to the number of a complete system, some of whose
attributes are found in one source and some in the other. Suppose
that the adornments describing access to the Computers
relation are buuuu, ubbff, and uuubb, while
the adornments for Monitors are bfff and ubbb.
For the following query, give 2-3 feasible plans (exclude
any plans that are obviously more expensive than other
plans on your list):
Find all systems with a G4 processor running at 750 megahertz with 256
megabytes of memory, a 40 gigabyte disk, and a 17-inch monitor.
- (15 points) Describe a data management or
search problem which involves integrating information
from multiple web sources. For example, planning a vacation may require culling
information from online flight and hotel reservation systems, car rental
websites, and tourist guides. Filling your taxes online is another popular
example, especially around this time of year. Here we would require documents
detailing our income and benefits from employer HR websites, end of year
statements from our banks and investment companies, and online filing forms from
federal and state websites. Indicate which web sources you will use and how
they satisfy your information needs. Next discuss which approach to
information integration (federation, mediation, or warehousing) you would take
and why. Be specific. Include advantages and disadvantages, and tradeoffs.
Describe how you will extract information from the sources to answer queries.
For example, will you build wrappers? If so, how sensitive will they be to the
underlying sources, how will they be implemented,
and how will they adapt? How will
your wrappers or interfaces expose the underlying data and capabilities
of the sources to other components. For instance,
will they use relational schemas, flat files,
or information hierarchies? Are any indices necessary?
Finally, give 3 specific queries
that your solution approach would accommodate and for one of them provide a
feasible query plan.
- (15 points) Read one of the articles in the section on data warehouses in
the December 2001 issue of IEEE
Computer (if you are seeking access from a computer outside of the UD
network, you made need to may need to authenticate yourself here)
and write a 2 page (11pt Times
font, single-spaced, 1" margins) analysis of it. Your
analysis should contain about a page of text summarizing the article. Your
summary should answer the following questions: What problem does the paper
address? What solution approach was taken and why? What is the most central
contribution to the database community made in the paper? In addition, your
analysis should address the advantages and disadvantages of the solution, how it
scales, and how it aligns with existing approaches. Since these articles are
nearly 5 years old now, briefly discuss what new developments in the field of
database systems have augmented/superseded this work. Lastly, identify and
explain what new things you learned, beyond what we have covered class, by
reading this article.
- (10 points) Required only for CPS 562 students
We studied the usefulness of an SIX mode for multiple-granularity locking.
Explain why an exclusive and intension-shared (XIS) mode is of no use.