Set autotrace

[marist89]

set autotrace traceonly explain

SQL> select * from xyz;

         X Y         Z
---------- --------- --------------------
         1 22-OCT-03 foo

SQL> set autotrace traceonly explain
SQL> select * from xyz
  2  ;

Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=1 Bytes=34)
   1    0   TABLE ACCESS (FULL) OF 'XYZ' (Cost=1 Card=1 Bytes=34)