Oracle 查看执行计划

刚刚开始接触Oracle，使用的工具是Sql Developer。在看执行计划的的时候，选中SQL语句，直接F5即可。

但是这里的执行计划不是最终的执行计划，它使用的是 explain for 命令。

这里介绍个可查看真正执行计划的工具， autotrace ，下面是用法示例：

SQL> set autotrace
Usage: SET AUTOT[RACE] {OFF | ON | TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]]
SQL> set autot on
SQL> set timing on
SQL> select * from dual;

D
-
X

Elapsed: 00:00:00.00

Execution Plan
----------------------------------------------------------
Plan hash value: 272002086

--------------------------------------------------------------------------
| Id  | Operation      | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |     |     1 |     2 |     2   (0)| 00:00:01 |
|   1 |  TABLE ACCESS FULL| DUAL |     1 |     2 |     2   (0)| 00:00:01 |
--------------------------------------------------------------------------


Statistics
----------------------------------------------------------
      1  recursive calls
      0  db block gets
      2  consistent gets
      0  physical reads
      0  redo size
    522  bytes sent via SQL*Net to client
    519  bytes received via SQL*Net from client
      2  SQL*Net roundtrips to/from client
      0  sorts (memory)
      0  sorts (disk)
      1  rows processed

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