The SQL Tuning Advisor runs automatically during system maintenance windows (time periods) as a maintenance task. During each automatic run, the advisor selects high-load SQL queries in the system and generates recommendations on how to tune these queries.
The Automatic SQL Tuning Advisor can be configured to automatically implement SQL profile recommendations. A SQL profile contains additional SQL statistics that are specific to the SQL statement and enable the query optimizer to generate a significantly better execution plan at run time. If you enable automatic implementation, then the advisor creates SQL profiles for only those SQL statements where the performance improvement would be at least threefold. Other types of recommendations, such as the creation of new indexes, refreshing optimizer statistics, or restructuring SQL, can only be implemented manually. DML statements are not considered for tuning by the Automatic SQL Tuning Advisor.
You can view a summary of the results of automatic SQL tuning, and a detailed report about recommendations made for all SQL statements that the SQL Tuning Advisor has processed. You can then implement selected recommendations. You can also view the recommendations that were automatically implemented.
You can disable the Automatic SQL Tuning Advisor, if desired.