STATISTICS

2.355 STATISTICS_LEVEL

STATISTICS_LEVEL specifies the level of collection for database and operating system statistics. The Oracle Database collects these statistics for a variety of purposes, including making self-management decisions.

Property	Description
Parameter type	String
Syntax	`STATISTICS_LEVEL = { ALL \| TYPICAL \| BASIC }`
Default value	`TYPICAL`
Modifiable	`ALTER SESSION`, `ALTER SYSTEM`
Modifiable in a PDB	Yes
Basic	No

The default setting of TYPICAL ensures collection of all major statistics required for database self-management functionality and provides best overall performance. The default value should be adequate for most environments.

When the STATISTICS_LEVEL parameter is set to ALL, additional statistics are added to the set of statistics collected with the TYPICAL setting. The additional statistics are timed operating system statistics and plan execution statistics.

Setting the STATISTICS_LEVEL parameter to BASIC disables the collection of many of the important statistics required by Oracle Database features and functionality, including:

All server-generated alerts
Automatic Database Diagnostic Monitor (ADDM)
Automatic optimizer statistics collection
Automatic SGA Memory Management
Automatic Workload Repository (AWR) Snapshots
Buffer cache advisory
Database time distribution statistics (V$SESS_TIME_MODEL and V$SYS_TIME_MODEL)
End to End Application Tracing (V$CLIENT_STATS)
Monitoring of statistics
MTTR advisory
Object Activity Tracking System (OATS)
Object level statistics
PGA Target advisory
Segment level statistics
Service level statistics
Shared pool sizing advisory
Timed statistics

Note:

Oracle strongly recommends that you do not disable these important features and functionality.

When the STATISTICS_LEVEL parameter is modified by ALTER SYSTEM, all advisories or statistics are dynamically turned on or off, depending on the new value of STATISTICS_LEVEL. When modified by ALTER SESSION, the following advisories or statistics are turned on or off in the local session only. Their systemwide state is not changed:

Timed statistics
Timed operating system statistics
Plan execution statistics

The V$STATISTICS_LEVEL view displays information about the status of the statistics or advisories controlled by the STATISTICS_LEVEL parameter. See "V$STATISTICS_LEVEL".