OCP-1Z0-053-200题-64题-641
QUESTION 64
Which three functions are performed by the SQL Tuning Advisor? (Choose three.)
A. Building the SQL profile
B. Recommending optimization of materialized views
C. Checking query objects for missing and stale statistics
D. Recommending bitmap, function-based, and B-tree indexes
E. Recommending restructuring SQL queries that are using bad plans
Answer: ACE
同641题：http://blog.csdn.net/rlhua/article/details/16886693
Explanation/Reference:
Section: Managing Database Performance & Tuning
SQL Tuning Advisor Automatic SQL tuning is exposed through SQL Tuning Advisor.
SQL Tuning Advisor runs automatically during system maintenance windows as a maintenance task. During
each automatic run, the advisor selects high-load SQL queries in the database and generates
recommendations for tuning these queries.
SQL Tuning Advisor recommendations fall into the following categories:
- Statistics analysis
- SQL profiling
- Access path analysis
- SQL structure analysis
A SQL Profile contains additional statistics specific to a SQL statement and enables the optimizer to generate
a better execution plan. Essentially, a SQL profile is a method for analyzing a query. Both access path and
SQL structure analysis are useful for tuning an application under development or a homegrown production
application.
A principal benefit of SQL Tuning Advisor is that solutions come from the optimizer rather than external tools
(see "Overview of the Optimizer" on page 7-10). Thus, tuning is performed by the database component that is
responsible for the execution plans and SQL performance. The tuning process can consider past execution
statistics of a SQL statement and customizes the optimizer settings for this statement.
http://www.remote-dba.net/oracle_10g_new_features/tuning_advisor.htm
How the SQL Tuning Advisor Works:
The optimizer will work in the new tuning mode wherein it conducts an in-depth analysis to come up with a set
of recommendations, the rationale for them and the expected benefit if you follow the recommendations.When
working in tuning mode, the optimizer is referred to as the Automatic Tuning Optimizer (ATO).