Performance Tuning - Question 102

What should be two goals in tuning rollback segments? (Choose two)

A. Transactions should never wait for access to rollback segment.

B. No transaction, however large or exceptional, should ever run out of rollback space.

C. Rollback segments should be configured to extend continually during normal processing.

D. The ratio of waits to the rollback segment header blocks should be less than 5% of the sum of access.

Answer: A, B

Explanation:

There are two main goals for rollback segments: transactions should never wait for access to rollback segment; no transaction should ever run out of rollback space because it used to keep the read-consistent view of the changed data.

Incorrect Answers

C: Rollback should not extend continually during normal processing. It is possible only as exception to keep data for batch jobs performing DML operations with many rows.

D: Transactions should never wait for access to rollback segment.

OCP: Oracle 9i Performance Tuning Study Guide, Joseph C. Johnson, p. 425-429

Chapter 8: Tuning Disk I/O