我有以下查询，可以正常运行并且不需要花费很多时间
我们称之为查询1：
select t3.date2
,t4.date1
,case
when t4.date1 is null then
t3.date2
else
t4.date1
end check_date
,t3.dimension2
from (select max(date2) date2
,dimension2
from view1 t4
where measure2 > 0
group by dimension2) t3
left join (select max(t1.date1) date1
,t1.dimension1
from table1 t1
where dimension2 = 'some value'
and exists (select 1
from (select max(date2) date2
,dimension2
from view1
where measure2 > 0
group by dimension2) t2
where t1.date1 > t2.date2
and t1.dimension1 = t2.dimension2)
group by t1.dimension1) t4
on t3.dimension1 = t4.dimension1;
EXPLAIN PLAN FOR ABOVE QUERY:
-----------------------------------------------------------------------
| Id | Operation | Name |
-----------------------------------------------------------------------
| 0 | SELECT STATEMENT | |
| 1 | HASH JOIN RIGHT OUTER | |
| 2 | VIEW | |
| 3 | HASH GROUP BY | |
| 4 | HASH JOIN RIGHT SEMI | |
| 5 | VIEW | |
| 6 | HASH GROUP BY | |
| 7 | HASH JOIN RIGHT OUTER | |
| 8 | INDEX STORAGE FAST FULL SCAN| TABLEB |
| 9 | HASH JOIN RIGHT OUTER | |
| 10 | TABLE ACCESS STORAGE FULL | TABLEA |
| 11 | TABLE ACCESS STORAGE FULL | VIEW1 |
| 12 | TABLE ACCESS STORAGE FULL | TABLE1 |
| 13 | VIEW | |
| 14 | HASH GROUP BY | |
| 15 | HASH JOIN RIGHT OUTER | |
| 16 | INDEX STORAGE FAST FULL SCAN | TABLEB |
| 17 | HASH JOIN RIGHT OUTER | |
| 18 | TABLE ACCESS STORAGE FULL | TABLEA |
| 19 | TABLE ACCESS STORAGE FULL | VIEW1 |
-----------------------------------------------------------------------
现在，通过使用以前的“查询1”，我正在创建一个新查询。该查询不会引发任何错误，但是它需要永远的运行
select a
,b
,date1
,dimension
from table1 t5
where some_condition = 'some condition'
and some_column is null
and exists (select 1
from ('query 1 here') t6
where t5.dimension = t6.dimension2
and t5.date1 >= t6.check_date);
EXPLAIN PLAN FOR ABOVE QUERY:
-----------------------------------------------------------------------------
| Id | Operation | Name |
-----------------------------------------------------------------------------
| 0 | SELECT STATEMENT | |
| 1 | FILTER | |
| 2 | INLIST ITERATOR | |
| 3 | TABLE ACCESS BY INDEX ROWID BATCHED | TABLE1 |
| 4 | INDEX RANGE SCAN | TABLEC |
| 5 | FILTER | |
| 6 | NESTED LOOPS OUTER | |
| 7 | VIEW | |
| 8 | SORT GROUP BY | |
| 9 | HASH JOIN OUTER | |
| 10 | HASH JOIN OUTER | |
| 11 | TABLE ACCESS STORAGE FULL | VIEW1 |
| 12 | TABLE ACCESS STORAGE FULL | TABLEA |
| 13 | INDEX STORAGE FAST FULL SCAN | TABLEB |
| 14 | VIEW | |
| 15 | SORT GROUP BY | |
| 16 | HASH JOIN SEMI | |
| 17 | TABLE ACCESS BY INDEX ROWID BATCHED| TABLE1 |
| 18 | INDEX RANGE SCAN | TABLE1_N5 |
| 19 | VIEW | |
| 20 | SORT GROUP BY | |
| 21 | HASH JOIN OUTER | |
| 22 | HASH JOIN OUTER | |
| 23 | TABLE ACCESS STORAGE FULL | VIEW1 |
| 24 | TABLE ACCESS STORAGE FULL | TABLEA |
| 25 | INDEX STORAGE FAST FULL SCAN | TABLEB |
-----------------------------------------------------------------------------
我也有一个与上面类似的查询，但是代替了“这里的查询1”部分，我有一个非常简单的查询，例如“ select max（some date），dim from t group by dim”，它返回更多数据（我（当然可以），但是它运行很快并给了我一个结果，但是当与上述查询结合使用时，它会一直运行下去，我必须手动终止它
**我不是oracle / sql开发人员，我只是使用select查询来获取数据，有时当返回的数据太大时，我尝试直接在查询中进行转换以避免后处理