Some Way To Active Oracle Trace

Reading to Oracle Documentation the trace is facility provides performance information on individual SQL statements. It generates the following statistics for each statement:

• Parse, execute, and fetch counts
• CPU and elapsed times
• Physical reads and logical reads
• Number of rows processed
• Misses on the library cache
• Username under which each parse occurred
• Each commit and rollback

To enable Oracle Trace you can do the following :

 Option Number One :

alter session set sql_trace = true;

Disable it :

alter session set sql_trace = false;

Option Number two :

dbms_session.set_sql_trace (true);

dbms_session.set_sql_trace (false);

Option Number three:

dbms_support.start_trace (binds=>{true|false}, waits=>{true|false});

dbms_support.stop_trace;

Notice that package is not installed by default , Check
EVENT: 10046 “enable SQL statement tracing (including binds/waits)” [ID 21154.1]

There’s The most Common way to Trace your SQL and enable trace , there’s other way you can search on it via Google or Oracle Documentation , all you have to do is trying one of these options .

some Other Useful link :
1-Oracle Documentation 
2-Oracle traces description.
3-Enable Oracle Traces

Thank you
Osama