SQL Tuning Features
AWR and ADDM provide services to support
automatic SQL tuning. SQL Tuning Advisor and SQL Access Advisor
are the SQL tuning tools provided by Oracle.
AWR provides services to Oracle Database
10g to collect, maintain, and utilize the statistics for problem
detection and self-tuning. The AWR has an in-memory statistics
collection facility, which is useful for 10g components to
collect statistics. These metrics are stored in memory for
The memory version of the statistics is
written to disk regularly by a new background process called
MMON (Memory Monitor).
Oracle Database 10g captures and retains
this historical data without DBA intervention. The default
retention period is seven days
parameter setting of 10080
which was as
described in Chapter 4. The historic data is used for
analysis of performance problems that occurred in a certain time
period in the past and to do trend analysis.
review, some session and system statistics that are
retained in v$sessstat and v$sysstat are as