CHAPTER 14

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Implementing Query Hints

Placing hints in SQL is a common and simple approach to improve performance. Hints influence Oracle’s optimizer to take a specific path to accomplish a given task, overriding the default path the optimizer may have chosen. Hints can also be viewed as a double-edged sword. If not implemented and maintained properly, they can hurt performance in the long run.

The initial goal of any application should be to implement SQL without hints because over time an application and its data can change, the database can be upgraded, hardware can change, and other factors can affect performance. Hints help an application ...

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