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.
Explanation:
Purpose of SQL Plan Baselines
Common 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. Most of these plan changes result in either no
performance change or improvement. However, some plan changes may cause
performance regressions. SQL plan baselines significantly minimize potential regressions
resulting from an upgrade.Ongoing system and data changes can impact plans for some SQL statements, potentially
causing performance regressions. SQL plan baselines help minimize performance
regressions and stabilize SQL performance.
Deployment of new application modules means introducing new SQL statements into the
database. The application software may use appropriate SQL execution plans developed in
a standard test configuration for the new statements. If the system configuration is
significantly different from the test configuration, then the database can evolve SQL plan
baselines over time to produce better performance.