Stored outlines :
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Stored outlines to freeze the plan, but that also means that you‘re preventing the optimizer from generating potentially beneficial execution plans.
SQL plan baseline :
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When SQL plan management is enabled, the optimizer stores generated execution plans in a special repository, the SQL management base. All stored plans for a specific SQL statement are said to be part of a plan history for that SQL statement.
Some of the plans in the history can be marked as “accepted.”When the SQL statement is reparsed, the optimizer considers only the accepted plans in the history. This set of accepted plans for that SQL statement is called a SQL plan baseline , or baseline for short.
With SQL plan management, you can examine all the available plans in the plan history for a SQL statement, compare them to see their relative efficiency, promote a specific plan to accepted status, and even make a plan the permanent (fixed) one.
You can create a SQL plan baseline in several ways: using a SQL Tuning Set (STS); from the cursor cache; exporting from one database and importing into another; and automatically for every statement
you can evolve a SQL plan baseline either by executing the evolve_sql_plan_baseline function or by using the SQL Tuning Advisor.
select sql_text, plan_name, enabled, accepted from dba_sql_plan_baselines;
SQL PROFILE :
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The query optimizer normally uses information like object and system statistics, compilation environment, bind values and so on to determine the best plan for a SQL statement.
In some cases, defects in either these inputs or the optimizer can lead to a sub-optimal plan. A SQL profile contains auxiliary information that mitigates these problems. When used together with its regular inputs, a SQL profile helps the optimizer minimize mistakes and thus more likely to select the best plan.
