053-001

1.While deploying a new application module, the software vendor ships the application software along
with appropriate SQL plan baselines for the new SQLs being introduced. Which two statements describe
the consequences? (Choose two.)
A. The plan baselines can be evolved over time to produce better performance.
B. The newly generated plans are directly placed into the SQL plan baseline without being verified.
C. The new SQL statements initially run with the plans that are known to produce good performance
under standard test configuration.
D. The optimizer does not generate new plans for the SQL statements for which the SQL plan baseline
has been imported.
Answer: AC

解析:

Common usage scenarios where SQL plan management can improve or preserve SQL performance include:

A database upgrade that installs a new optimizer version usually results in plan changes for a small percentage of SQL statements, with most of the plan changes resulting in either no performance change or improvement. However, certain plan changes may cause performance regressions. The use of SQL plan baselines significantly minimizes potential performance regressions resulting from a database upgrade.

Ongoing system and data changes can impact plans for some SQL statements, potentially causing performance regressions. The use of SQL plan baselines will help to minimize performance regressions and stabilize SQL performance.

Deployment of new application modules means introducing new SQL statements into the system. The application software may use appropriate SQL execution plans developed under a standard test configuration for the new SQL statements. If your system configuration is significantly different from the test configuration, the SQL plan baselines can be evolved over time to produce better performance.

参考:

http://docs.oracle.com/cd/B28359_01/server.111/b28274/optplanmgmt.htm