What Is the SQL Explain Plan?
The explain plan illustrates the execution plan for any SQL statement. It shows the tables and indexes Oracle will use when processing an SQL statement, as well as the order in which the tables and indexes will be used. The execution plan is the order of events that Oracle will follow to access data and process the SQL statement. The explain plan and execution plan are determined when SQL is presented to Oracle for execution. If an SQL statement's actual code does not change and the SQL statement is still in the library cache, Oracle will simply reuse the original execution plan.
Oracle9i enables you to store and reuse this execution plan, which is known as stored outlines, this feature was introduced in Oracle8i. ...
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