查看执行计划的方法有很多种，笔者今后将在博客里一一为大家介绍。本文介绍的是第一种方法，利用explain plan命令来查看执行计划
查看执行计划的方法有很多种，笔者今后将在博客里一一为大家介绍。本文介绍的是第一种方法，利用explain plan命令来查看执行计划。
1.用hr用户登录数据库
[Oracle@ENMOEDU ~]$ sqlplus hr/oracle@ENMOEDU
SQL*Plus: Release 11.2.0.3.0 Production on Thu Apr 10 00:11:00 2014
Copyright (c) 1982, 2011, Oracle.本文来源gao@!dai!ma.com搞$$代^@码!网 All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 – Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
HR@ENMOEDU >
2.使用explain plan命令
HR@ENMOEDU > explain plan for select salary from employees where first_name like ‘Pat’;
Explained.
3.查看执行计划
HR@ENMOEDU > select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
————————————————————————
Plan hash value: 3033625502
——————————————————————————————-
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
——————————————————————————————-
| 0 | SELECT STATEMENT | | 1 | 11 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| EMPLOYEES | 1 | 11 | 2 (0)| 00:00:01 |
|* 2 | INDEX SKIP SCAN | EMP_NAME_IX | 1 | | 1 (0)| 00:00:01 |
——————————————————————————————-
Predicate Information (identified by operation id):
—————————————————
2 – access(“FIRST_NAME”=’Pat’)
filter(“FIRST_NAME”=’Pat’)
15 rows selected.
至此，，执行计划查看成功。
转载请注明原文链接：查看执行计划方法总结之一:explain plan命令
