1. Week 6 Query Processing and Optimization Techniques
summary
Real-life example
 Query Processing
 Translating SQL queries into RA
 Evaluation Plan
 Query Execution
 Query Optimization
 Translation Rules
 Cost Estimations
quiz

2. Week 6 Query Processing and Optimization Techniques
summary
Real-life example
quiz
Let us take an example of a database with the following tables:
Book (Book No, Book Title)
Member (Member No, Member Name)
Loan(Book No, Member No, Loan Date)
Let us say we had lost a book whose title is ‘Zeus’ and we want to
know the name of the member who was its last borrower.
Meanwhile we have 300000 members, 10,000,000 books and
500,000,000 records about loans.
There are many ways of finding the name of the member who was
its last borrower.
• Making the Cartesian product of Book, Member and Loan before
looking for the title ‘Zeus’ and then the borrower.
• Making the Cartesian product of Book and Loan before looking the title ‘Zeus’.
Then make a join of the result with Member for checking who the last
borrower was.

3. Week 6 Query Processing and Optimization Techniques
summary
Real-life example
quiz
• Making the Cartesian product of Member and Loan. Then make a join of the
result with Book for checking what the book was and who the last borrower
was.
• Looking for the book ‘Zeus’ in Book, then looking for the book ‘Zeus’ in Loan
this will give the ‘Member No’ and at the end use the ‘Member No’ in
Member to find the name of the member.
• Etc.
Among the different solutions attempted, some are more optimized than others.
For instance, making the Cartesian product of all tables before looking for the title
‘Zeus’ and then the borrower is the longest way to find the answer since it will
generate 300,000*10,000,000*500,000,000 records among which to look for one
answer.
Finding the shortest way that consume less resources than other ways and
executes faster than others is the goal of Query processing and Optimization
Techniques.

4. Week 6 Query Processing and Optimization Techniques
summary
Real-life example
quiz
1. What is query processing?
A. The activities involved in entering in a database.
B. The activities involved in creating a database.
C. The activities involved in retrieving data from the database.
D. The activities involved in modifying a database.
2. What is relational algebra?
A. The basic set of operations for the relational model
B. SQL
C. DML
D. The activities involved in modifying a database.
3. Query optimization is a function of many relational database management
systems in which multiple query plans for satisfying a query are examined
and a good query plan is identified:
A. True
B. False
Enter answer,,,.
1.
2.
3.

5. Week 6 Query Processing and Optimization Techniques
summary
Real-life example
quiz
1. What is query processing?
A. The activities involved in entering in a database.
B. The activities involved in creating a database.
C. The activities involved in retrieving data from the database.
D. The activities involved in modifying a database.
2. What is relational algebra?
A. The basic set of operations for the relational model
B. SQL
C. DML
D. The activities involved in modifying a database.
3. Query optimization is a function of many relational database management
systems in which multiple query plans for satisfying a query are examined
and a good query plan is identified:
A. True
B. False
Enter answer,,,.
1. C
2. B
3. A

6. Week 6 Query Processing and Optimization Techniques
summary
Real-life example
quiz
4. What is not a translation rule?
A. Cascade of select
B. Commutativity of select
C . Cascade of project
D. Commuting select with join
E. Commuting rename
5. Cost estimations is the process of estimating and comparing costs of executing
query using different execution strategies:
A. True
B. False
answer is:
4.
5.

7. Week 6 Query Processing and Optimization Techniques
summary
Real-life example
quiz
4. What is not a translation rule?
A. Cascade of select
B. Commutativity of select
C . Cascade of project
D. Commuting select with join
E. Commuting rename
5. Cost estimations is the process of estimating and comparing costs of executing
query using different execution strategies:
A. True
B. False
answer is:
4. E
5. A