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Explain how oracle optimizer works.Oracle optimizer determines the best possible way to execute a query. This optimizer uses internal set of rules or costing methods to ace hove the result. The output from the optimizer is a plan that describes an optimum method of execution the optimizer first evaluates expressions and conditions containing constants as fully as possible. Here after it chooses either a cost-based or rule-based approach and determines the goal of optimization. For each table accessed it chooses one access path from the available ones Explain how oracle optimizer works.The optimization is determining the most efficient way to execute a SQL statement after considering the factors related to the objects referenced and the conditions specified in the query.
This determination is an important step in the processing of any SQL statement and can greatly affect execution time.
The optimizer first evaluates expressions and conditions containing constants.Then Statement transformation follows which is followed by Choice of optimizer approaches. Then is the Choice of access paths followed by Choice of join orders and finally the Choice of join methods.
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