Home » Oracle » 1z0-117 » Which two are true about the execution of this query?
You enabled auto degree of parallelism (DOP) for your instance.
Examine the query:
Which two are true about the execution of this query?
A. Dictionary DOP will be used, ifpresent, on the tables referred in the query.
B. DOP is calculated if the calculated DOP is 1.
C. DOP is calculated automatically.
D. Calculated DOP will always by 2 or more.
E. The statement will execute with auto DOP only when PARALLEL_DEGREE_POLICY is set to AUTO.
Correct Answer: CD
Explanation/Reference:
C:*You can use the PARALLEL hint to force parallelism. It takes an optional parameter: the DOP at which the statement should run. In addition, theNO_PARALLEL hint overrides a PARALLEL parameter in the DDL that created or altered the table.
The following example illustrates computing the DOP the statement should use:
SELECT /*+ parallel(auto) */ ename, dname FROM emp e, dept d
WHERE e.deptno=d.deptno;
Not A: to override the dictionary dop,we could use hints at object level
Not E: statement hints overridethePARALLEL_DEGREE_POLICY.
Note:
*Automatic Parallel Degree Policy
When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle Database automatically decides if a statement should execute in parallel or not and what DOP it should use.
Oracle Database also determines if the statement can be executed immediately or if it is queued until more system resources are available. Finally, Oracle Database decides if the statement can take advantage of the aggregated cluster memory or not.
The following is a summary of parallel statement processing when parallel degree policy is set to automatic.
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