oracle 10g 执行计划(explain plan)更为简单
一:举个最简单例子:
执行SQL语句
explain plan for select count(*)from fxusers;
查询执行计划
select*from table(dbmsxplan.display);
PLANTABLEOUTPUT
--------------------------------------------------------------------------------
Plan hash value:1895104989
---------------------------------------------------------------------
|Id|Operation|Name|Rows|Cost(%CPU)|Time|
---------------------------------------------------------------------
|0|SELECT STATEMENT||1|1(0)|00:00:01|
|1|SORT AGGREGATE||1|||
|2|INDEX FULL SCAN|UNUSERS|13|1(0)|00:00:01|
---------------------------------------------------------------------
就这么简单啊!
二绑定变量执行计划
执行SQL语句
explain plan for select count(*)from fxusers where username=:p;
查询执行计划
select*from table(dbmsxplan.display);
PLANTABLEOUTPUT
--------------------------------------------------------------------------------
Plan hash value:2217371508
------------------------------------------------------------------------------
|Id|Operation|Name|Rows|Bytes|Cost(%CPU)|Time|
------------------------------------------------------------------------------
|0|SELECT STATEMENT||1|99|3(0)|00:00:01|
|*1|TABLE ACCESS FULL|FXUSERS|1|99|3(0)|00:00:01|
------------------------------------------------------------------------------
Predicate Information(identified by operation id):
---------------------------------------------------
1-filter(TONUMBER("USERNAME")=1)