Figure 6-9. A representation of Oracle CBC structure consisting of two CBC latches, six cache buffer chains, and eleven buffer headers. Notice both control structures (CS 800 and CS 810) cover three CBCs, reducing the likelihood of CBC latch contention.

Let's now put this all together and walk through an example. Figure 6-9 will represent the entire CBC structure. In this example, I will make certain abstractions or simplifications, focusing on areas that I have already covered and that are useful for performance firefighting. As you progress through the next chapters, the story will become increasingly detailed, bringing together all that you've learned.

Suppose you are a server process executing a SQL statement. Based on the SQL statement and Oracle's data dictionary, you discover there is row you must access located in file number 35 with a block number of 2435.