Chapter 7: Database Concurrency

Overview

Eleven percent (11%) of the DB2 9 Fundamentals certification exam (Exam 730) is designed to test your knowledge of the mechanisms DB2 9 uses to allow multiple users and applications to interact with a database simultaneously without negatively affecting data consistency. The questions that make up this portion of the exam are intended to evaluate the following:

• Your ability to identify the appropriate isolation level to use for a given situation

• Your ability to identify the characteristics of locks

• Your ability to list objects for which locks can be acquired

• Your ability to identify factors that can influence locking

This chapter is designed to introduce you to the concept of data consistency and to isolation levels and locks-the mechanisms DB2 uses to maintain data consistency in both single- and multi-user database environments.