Oracle8i SQL Reference Release 2 (8.1.6) A76989-01 |
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SQL Statements (continued), 16 of 20
To create a stored outline, which is a set of attributes used by the optimizer to generate an execution plan. You can then instruct the optimizer to use a set of outlines to influence the generation of execution plans whenever a particular SQL statement is issued, regardless of changes in factors that can affect optimization. (To modify an outline so that it takes into account changes in these factors, see "ALTER OUTLINE".)
You enable or disable the use of stored outlines dynamically for an individual session or for the system. See "ALTER SESSION" and "ALTER SYSTEM".
To create an outline, you must have the CREATE
ANY
OUTLINE
system privilege.
The following statement creates a stored outline by compiling the ON
statement. The outline is called SALARIES and is stored in the category SPECIAL
.
CREATE OUTLINE salaries FOR CATEGORY special ON SELECT ename, sal FROM emp;
When this same SELECT
statement is subsequently compiled, if the USE_STORED_OUTLINES
parameter is set to SPECIAL
, Oracle generates the same execution plan as was generated when the outline SALARIES
was created.
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