One of the most difficult challenges that the real-world DBA faces is performance tuning. Performance tuning is the process of using database configuration mechanisms to achieve optimal application throughput. It is a career-long study that requires a keen understanding of the way that a database works, from memory caches to process configuration to the topic of this chapter—concurrency. Concurrency is the property that enables systems with many competing resources to function optimally. Maintaining concurrency in the Oracle RDBMS involves rules, mechanisms, and configuration settings.
In this chapter we shall:
Understand the lifecycle of a transaction
Explain the concept of the undo process
Learn to manage undo data
Explore database locking mechanisms
Understand latches and mutexes