Chapter 15. Lock Contention

This chapter is the first of several that deal with the various types of contention that commonly inflict Oracle databases.

As we discussed in Chapter 1, “Oracle Performance Tuning: A Methodical Approach,” contention occurs when two or more sessions attempt to simultaneously utilize limited or serialized resources. Contention limits the amount of work that the database can get done because sessions queue up for the limited resources concerned.

We introduced the concepts of transactions and locking in Chapter 4, “Logical and Physical Database Design.” The ACID (Atomic-Consistent-Independent-Durable) properties of transactions, especially the consistency characteristic, require that Oracle limit concurrent changes to ...

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