Base Statistics, Metrics, and Statistics
Base statistics represent the raw data that
is collected. Metrics are secondary statistical data derived
from base statistics. Most of the 10g metrics are used to track
the rates of change of activities in the Oracle database.
Metrics are used by internal components for system health
monitoring, problem detection, and self-tuning. Oracle Database
10g has metrics for session, system, file, and wait-event
The advantage of having metrics is the
ready availability of data for a component to compute the rate
of change related to selected activities. In previous versions,
statistics had to be gathered before and after running a job to
compute the changed rate for base statistics. By using metrics,
the information can be derived directly after running the job.
Statistics Levels can be captured by using
the statistics_level initialization parameter. This
parameter has three values: BASIC, TYPICAL, and ALL.