In Oracle Database 11g the internal implementation for nested loop joins changed to reduce overall latency for physical I/O so it is possible you will see two NESTED LOOPS joins in the operations column of the plan, where you previously only saw one on earlier versions of Oracle. Figure 18...
for example—you can connect to the database as a DBA user and invoke the dbms_system built-in package in order to turn on or off SQL trace in another session. You