statistic_level

statistic_level
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Property         |    Description
Parameter type    |    String
Syntax           |    STATISTICS_LEVEL = { ALL | TYPICAL | BASIC }
Defaultvalue    |    TYPICAL
Modifiable       |     ALTERSESSION, ALTER SYSTEM
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STATISTICS_LEVELspecifies the level of collection for database andoperating
system statistics. The Oracle Database collects these statisticsfor a variety of purposes,
including making self-management decisions.
The default setting of TYPICALensures collection of all majorstatistics required for
database self-management functionality and provides best overallperformance. The
default value should be adequate for most environments.
When the STATISTICS_LEVELparameter is set to ALL, additionalstatistics are added
to the set of statistics collected with the TYPICALsetting. Theadditional statistics are
timed OS statistics and plan execution statistics.

Setting the STATISTICS_LEVELparameter to BASIC disables thecollection of many
of the important statistics required by Oracle Database featuresand functionality,
including:
■ Automatic Workload Repository (AWR) Snapshots
■ Automatic Database Diagnostic Monitor (ADDM)
■ All server-generated alerts
■ Automatic SGA Memory Management
■ Automatic optimizer statistics collection
■ Object level statistics
■ End to End Application Tracing (V$CLIENT_STATS)
■ Database time distribution statistics (V$SESS_TIME_MODELandV$SYS_TIME_
MODEL)
■ Service level statistics
■ Buffer cache advisory
■ MTTR advisory
■ Shared pool sizing advisory
■ Segment level statistics
■ PGA Target advisory
■ Timed statistics
■ Monitoring of statistics