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