set autotrace常用操作

SQL> set autotrace
用法: SET AUTOT[RACE] {OFF | ON | TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]]


--用法1：查看执行计划、统计信息并且返回sql结果集
set autotrace on; 


select count(*) from t;  
  
  COUNT(*)  
----------  
     50295  
  
已用时间:  00: 00: 00.01  
  
执行计划  
----------------------------------------------------------  
Plan hash value: 2966233522  
  
-------------------------------------------------------------------  
| Id  | Operation          | Name | Rows  | Cost (%CPU)| Time     |  
-------------------------------------------------------------------  
|   0 | SELECT STATEMENT   |      |     1 |   159   (2)| 00:00:02 |  
|   1 |  SORT AGGREGATE    |      |     1 |            |          |  
|   2 |   TABLE ACCESS FULL| T    | 50295 |   159   (2)| 00:00:02 |  
-------------------------------------------------------------------  
  
  
统计信息  
----------------------------------------------------------  
          0  recursive calls  
          0  db block gets  
          0  consistent gets  
          0  physical reads  
          0  redo size  
        509  bytes sent via SQL*Net to client  
        211  bytes received via SQL*Net from client  
          2  SQL*Net roundtrips to/from client  
          1  sorts (memory)  
          0  sorts (disk)  
          1  rows processed  



---方法2：查看执行计划、统计信息不返回sql结果集：


SQL> set autotrace traceonly;  
SQL> select * from t2;  
  
已选择402344行。  
  


  
执行计划  
----------------------------------------------------------  
Plan hash value: 1513984157  
  
--------------------------------------------------------------------------  
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |  
--------------------------------------------------------------------------  
|   0 | SELECT STATEMENT  |      |   402K|    33M|  1240   (3)| 00:00:15 |  
|   1 |  TABLE ACCESS FULL| T2   |   402K|    33M|  1240   (3)| 00:00:15 |  
--------------------------------------------------------------------------  
  
  
统计信息  
----------------------------------------------------------  
          0  recursive calls  
          0  db block gets  
          0  consistent gets  
          0  physical reads  
          0  redo size  
        911  bytes sent via SQL*Net to client  
        190  bytes received via SQL*Net from client  
          2  SQL*Net roundtrips to/from client  
          1  sorts (memory)  
          0  sorts (disk)  
     402344  rows processed  






---方法3：只看执行计划不返回sql结果集：


QL> set autotrace traceonly explain;  
SQL> select * from t;  
已用时间:  00: 00: 00.01  
  
执行计划  
----------------------------------------------------------  
Plan hash value: 1601196873  
  
--------------------------------------------------------------------------  
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |  
--------------------------------------------------------------------------  
|   0 | SELECT STATEMENT  |      | 50295 |  4273K|   161   (3)| 00:00:02 |  
|   1 |  TABLE ACCESS FULL| T    | 50295 |  4273K|   161   (3)| 00:00:02 | 






---方法4：只看统计信息不返回sql结果集：




SQL> set autotrace traceonly statistics;  
SQL> select * from t;  
  
已选择50295行。  
  
  
统计信息  
----------------------------------------------------------  
          0  recursive calls  
          0  db block gets  
          0  consistent gets  
          0  physical reads  
          0  redo size  
        911  bytes sent via SQL*Net to client  
        189  bytes received via SQL*Net from client  
          2  SQL*Net roundtrips to/from client  
          1  sorts (memory)  
          0  sorts (disk)  
      50295  rows processed