1，cd  [oracle_home]\rdbms\admin;
2, run  @utlxplan;
3, create public synonym plan_table to public; --no need to run in oracle10,oracle default
4, grant all on plan_table to public;--no need to run in oracle10,oracle default, here public can be any user;
----create role plustrace and grant it to user
1, cd [oracle_home]\sqlplus\admin;
2, conn sqlplus as sysdba;
3, run @plustrce;
4, grant plustrace to public;
---test
 1, conn sqlplus with user scott;
1.1, set autotrace on; 
 2, run : select * from dual;
 3, show stat info;
--1.1 可選項： set autotrace off: 不生成報告，默認；
                           set autotrace on explain: 報告只顯示優化器執行路徑；
                           set autotrace on statistics: 報告只顯示sql語句執行統計信息；
                           set autotrace on: 報告顯示優化器執行路徑，sql語句統計信息；
                            set autotrace traceonly: 報告顯示優化器執行路徑，sql語句統計信息，不顯示查詢輸出；

                          
ref：oracle 9i、10g編程藝術。