CHAPTER

19

Query Optimizer

In This Chapter

•   Phases of Query Processing

•   How Query Optimization Works

•   Tools for Editing the Optimizer Strategy

•   Optimizer Hints

The question that generally arises when the Database Engine (or any other relational database system) executes a query is how the data that is necessary for the query can be accessed and processed in the most efficient manner. The component of a database system that is responsible for the processing is called the query optimizer.

The task of the query optimizer (or just optimizer) is to consider a variety of possible execution strategies for querying the data in relation to a given query and to select the most efficient strategy. The selected strategy is called the ...

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