Database Reference
In-Depth Information
Figure 9-43.
SQL plans created as part of SQL profiles
The benefit of having one view for all plan control is that if a statement has changed and there is a question about
whether plan control is in place, the DBA can easily access and verify from the panel instead o having to search for the
SQL ID.
Optimizer Statistics
Statistics are the core of Oracle's Cost-Based Optimizer (CBO.) As an administrator deepens their knowledge of
performance and optimization, their knowledge of statistics must increase as well. EM12c offers a number of
graphical user interfaces to lessen demands on command-line requirements, but the knowledge of how statistics help
the CBO make optimization choices is a key to any Oracle database specialist's skill set.
Graphic options to gather, restore, lock, and manage statistics are a powerful tool in the hands of an
administrator. The Performance drop-down menu of the database target in EM12c enables you to set default options
for optimizer statistics, along with addressing performance issues with the CBO (see Figure
9-44
).
