Questions from Database Systems

Q: Explain why logical undo logging is used widely, whereas logical redo

Explain why logical undo logging is used widely, whereas logical redo logging (other than physiological redo logging) is rarely used.

Q: Consider the log in Figure 19.5. Suppose there is

Consider the log in Figure 19.5. Suppose there is a crash just before the log

Q: Using the university schema, write an SQL query to find the

Using the university schema, write an SQL query to find the ID and title of each course in Comp. Sci. that has had at least one section with afternoon hours (i.e., ends at or after 12:00). (You should...

Q: Suppose there is a transaction that has been running for a very

Suppose there is a transaction that has been running for a very long time but has performed very few updates. a. What effect would the transaction have on recovery time with the recovery algorithm of S...

Q: Consider a bank that has a collection of sites, each running

Consider a bank that has a collection of sites, each running a database system. Suppose the only way the databases interact is by electronic transfer of money between themselves, using persistent mess...

Q: If an enterprise uses its own ERP application on a cloud service

If an enterprise uses its own ERP application on a cloud service under the platform-as-a-service model, what restrictions would there be on when that enterprise may upgrade the ERP system to a new ver...

Q: Consider the schemas for the table people, and the table’s students

Consider the schemas for the table people, and the table’s students and teachers, which were created under people, in Section 8.2.1.3. Give a relational schema in third normal form that represents the...

Q: Assume that a growing enterprise has outgrown its current computer system and

Assume that a growing enterprise has outgrown its current computer system and is purchasing a new parallel computer. If the growth has resulted in many more transactions per unit time, but the length...

Q: Database systems are typically implemented as a set of processes (or

Database systems are typically implemented as a set of processes (or threads) accessing shared memory. a. How is access to the shared-memory area controlled? b. Is two-phase locking appropriate for se...

Q: Is it wise to allow a user process to access the shared

Is it wise to allow a user process to access the shared-memory area of a database system? Explain your answer.