有点意思

定制自己的执行计划

explain plan for select * from emp a

join dept b

on a.deptno = b.deptno

where a.sal<3000;

delete plan_table

select * from plan_table;--只能执行一次

--从id=0开始，查找id=0左右的儿子

--prior 在哪边，优先显示哪边

select id "id",

lpad(' ',level) ||operation||' ' ||options "operation",

object_name "Name",

cardinality "Rows"

from plan_table a

start with id = 0

connect by prior id = parent_id;

当access_predicates,filter_predicates 任意一个不为空，id前面就有*，并显示出来

自己写：

select case when access_predicates is not null or filter_predicates is not null then '*'

else ' '

end || id "id",

lpad(' ', level) || operation || ' ' || options "operation",

object_name "Name",

cardinality "Rows",

access_predicates,

filter_predicates

from plan_table a

start with id = 0

connect by prior id = parent_id;

官方：

select case

when access_predicates is not null or filter_predicates is not null then

'*'

else

' '

end || id "Id",

lpad(' ', level) || operation || ' ' || options "Operation",

object_name "Name",

cardinality "Rows",

access_predicates,

filter_predicates

from plan_table a

start with id = 0

connect by prior id = parent_id;