AUTOTRACE一般有以下用法：
SQL> set autotrace
用法: SET AUTOT[RACE] {OFF | ON | TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]]
一、輸出查詢結果
1.set autotrace on 輸出結果和訪問路徑以及統計信息
2.set autotrace on explain 輸出結果和訪問路徑
3.set autotrace on statistics 輸出結果和統計信息
二、不輸出查詢結果
1.set autotrace traceonly 只輸出訪問路徑以及統計信息
以下是舉例：
-- 1.set autotrace on：
SQL> set line 300
SQL> set pages 20
SQL> set autotrace on
SQL> select * from emp ;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
...(節省篇幅)
已選擇14行。
執行計劃
----------------------------------------------------------
Plan hash value: 3956160932
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 14 | 532 | 3 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| EMP | 14 | 532 | 3 (0)| 00:00:01 |
--------------------------------------------------------------------------
統計信息
----------------------------------------------------------
0 recursive calls
0 db block gets
8 consistent gets
0 physical reads
0 redo size
1631 bytes sent via SQL*Net to client
520 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
14 rows processed
-- 2. set autotrace on explain
SQL> set autotrace on explain
SQL> /
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
...（節省篇幅）
已選擇14行。
執行計劃
----------------------------------------------------------
Plan hash value: 3956160932
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 14 | 532 | 3 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| EMP | 14 | 532 | 3 (0)| 00:00:01 |
--------------------------------------------------------------------------
-- 3.
SQL> set autotrace on statistics
SQL> /
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
...（節省篇幅）
已選擇14行。
統計信息
----------------------------------------------------------
0 recursive calls
0 db block gets
8 consistent gets
0 physical reads
0 redo size
1631 bytes sent via SQL*Net to client
520 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
14 rows processed
二、
set autotrace traceonly
SQL> set autotrace traceonly
SQL> /
已選擇14行。
執行計劃
----------------------------------------------------------
Plan hash value: 3956160932
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 14 | 532 | 3 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| EMP | 14 | 532 | 3 (0)| 00:00:01 |
--------------------------------------------------------------------------
統計信息
----------------------------------------------------------
0 recursive calls
0 db block gets
8 consistent gets
0 physical reads
0 redo size
1631 bytes sent via SQL*Net to client
520 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
14 rows processed