Statistic Levels

You determine the level of statistic collection on the database by setting the value of the STATISTICS_LEVEL parameter. The values for this parameter are:

• BASIC: No advisory or other statistical data is collected. You can manually set other statistic collection parameters such as TIMED_STATISTICS and DB_CACHE_ADVICE. Many of the statistics required for a performance baseline are not collected. Oracle strongly recommends that you do not disable statistic gathering. 
• TYPICAL: This is the default value. Data is collected for segment-level statistics, timed statistics, and all advisories. The value of other statistic collection parameters is overridden.
• ALL: Collection is made of all the TYPICAL level data, the timed operating system statistics, and the row source execution statistics. The value of other statistic collection parameters is overridden.

Query V$STATISTICS_LEVEL to determine which other parameters are affected by the STATISTICAL_LEVEL parameter.

 select statistics_name, activation_level 

 from v$statistics_level

 order by 2;