The automatic SQL tuning set (ASTS) is a system-maintained record of SQL execution plans and SQL statement performance metrics seen by the database. Over time, the ASTS will include examples of all queries seen on the system.
SQL plans and metrics stored in ASTS are useful for repairing SQL performance regressions quickly using SQL plan management.
ASTS enables SQL performance regressions to be resolved quickly and with minimal manual intervention. It is complementary to the automatic workload repository (AWR) and considered a similar core manageability infrastructure of the Oracle Database.