IT 344

Question Two

4 Marks

Learning Outcome(s):

Be able to analyze an algorithm for query processing and to optimize it.

Give a brief explanation of why the following query may not be promoting the query optimizer to use any index and show how it can be improved to be able to use an index.

SELECT ESSN, FName, LName, Salary, Age

FROM EMPLOYEE

WHERE Age < 35 OR Salary < 2000

Question Three


3 Marks



Learning Outcome(s):

Learn and understand transaction management, concurrency, and recovery of a database.






What is a schedule? How many number of serial schedules can be formed with 3 transactions? Write down all serial schedule.



	
Question Four


6 Marks



Learning Outcome(s):

Learn and understand transaction management, concurrency, and recovery of a database.









Check whether the schedules is conflict serializable or not? If yes, then why? Explain by drawing precedence graph.


a) S: R2(A); W2(A); R3(C); W2(B); W3(A); W3(C); R1(A);


                 R1(B); W1(A); W1(B)


b) S: R2(A); R3(C); W3(A); W2(A); W2(B); W3(C); R1(A);


                R1(B); W1(A); W1(B)

Question Five


3 Marks



Learning Outcome(s):

Learn and understand transaction management, concurrency, and recovery of a database.


What are the problems they may encounter when the transactions are run concurrently? Explain with examples.