Questions from Database Systems

Q: List four applications you have used that most likely employed a database

List four applications you have used that most likely employed a database system to store persistent data.

Q: Use Armstrong’s axioms to prove the soundness of the decomposition rule.

Use Armstrong’s axioms to prove the soundness of the decomposition rule.

Q: During its execution, a transaction passes through several states, until

During its execution, a transaction passes through several states, until it finally commits or aborts. List all possible sequences of states through which a trans- action may pass. Explain why each sta...

Q: Write the following queries in relational algebra, using the university schema

Write the following queries in relational algebra, using the university schema. a. Find the ID and name of each instructor in the Physics department. b. Find the ID and name of each instructor in a de...

Q: Explain the distinction between the terms serial schedule and serialize able schedule

Explain the distinction between the terms serial schedule and serialize able schedule.

Q: Consider the following two transactions: / Let the consistency

Consider the following two transactions: Let the consistency requirement be A = 0 ∨ B = 0, with A = B = 0 as the initial values. a. Show that every serial execution involving t...

Q: Give an example of a serialize able schedule with two transactions such

Give an example of a serialize able schedule with two transactions such that the order in which the transactions commit is different from the serialization order.

Q: What is a recoverable schedule? Why is recoverability of schedules desirable

What is a recoverable schedule? Why is recoverability of schedules desirable? Are there any circumstances under which it would be desirable to allow non- recoverable schedules? Explain your answer.

Q: Why do database systems support concurrent execution of transactions, de-

Why do database systems support concurrent execution of transactions, de- spite the extra effort needed to ensure that concurrent execution does not cause any problems?

Q: Explain why the read-committed isolation level ensures that schedules are

Explain why the read-committed isolation level ensures that schedules are cascade-free.