C H A P T E R 5
Caches and Copies
Caching means keeping copies of things that we expect to use soon, and keeping them close by so that we can access them quickly. Chapter 2 described how Oracle changes various types of data blocks (including undo blocks) and showed you a few of the structures that you can see stored in blocks, but it didn’t say anything about how Oracle manages to keep a selection of recently used or popular blocks in memory. Chapter 2 simply assumed that whenever we needed a block, the correct version of that block would be available.
In Chapter 4, you saw a simplified diagram of the library cache and learned how you can use hash chains (or buckets) to ensure that you can find an object quickly, provided that you can work ...
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