Query with order by & View/procedure

Question

1)I have a query its getting joined with few tables and the base table contains 12 billion rows . my issue is when I execute the query with necessary parameter am getting the result in few seconds . but when I add an order by for any column am not getting the result even after 15 minuts.
The sort column is an indexed column and I have even tried with the primary column of the base table but no change .. is there any way to make it faster with order by ??
2)I have got a view which also getting joined with few high volume tables . when I call the view with required parameter am not getting the result even after 15 minutes.. but when I took out the query of the view and hardcode the value am getting the result in 3 seconds . so I just made it to a procedure that returns a cursor . now its working fine .. could you please explain me the reason for this ….??
Please help …

Answer 1

select * from
(select Rownum RowNO,Qr.* from
(select T1.c1,T2.C2,T3.c3 from TI,T2,T3
where < all required joins>
order by Ti.c)Qr
where RowNum <20 )
where RowNO >10 ;As said before:
Your view very likely prevented predicate pushing and by manually adding the predicate inside the query, you changed the semantics of the query.
Your view contains a rownum column. This prevents predicate pushing because the semantics of the query changes. An example to clarify:
SQL> explain plan
  2  for
  3  select *
  4    from ( select empno
  5                , ename
  6                , sal
  7             from emp
  8         )
  9   where empno = 7839
10  /
Uitleg is gegeven.
SQL> select * from table(dbms_xplan.display)
  2  /
PLAN_TABLE_OUTPUT
Plan hash value: 4024650034
| Id  | Operation                   | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |        |     1 |    14 |     1   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    14 |     1   (0)| 00:00:01 |
|*  2 |   INDEX UNIQUE SCAN         | EMP_PK |     1 |       |     0   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - access("EMPNO"=7839)
14 rijen zijn geselecteerd.
SQL> exec dbms_lock.sleep(1)
PL/SQL-procedure is geslaagd.
SQL> explain plan
  2  for
  3  select *
  4    from ( select empno
  5                , ename
  6                , sal
  7             from emp
  8            where empno = 7839
  9         )
10  /
Uitleg is gegeven.
SQL> select * from table(dbms_xplan.display)
  2  /
PLAN_TABLE_OUTPUT
Plan hash value: 4024650034
| Id  | Operation                   | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |        |     1 |    14 |     1   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    14 |     1   (0)| 00:00:01 |
|*  2 |   INDEX UNIQUE SCAN         | EMP_PK |     1 |       |     0   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - access("EMPNO"=7839)
14 rijen zijn geselecteerd.The previous two queries show that in this case the predicate "empno = 7839" can be pushed inside the view. Both queries are semantically the same.
However, when you add a rownum to your view definition, like you did, the predicates cannot be pushed inside the view:
SQL> exec dbms_lock.sleep(1)
PL/SQL-procedure is geslaagd.
SQL> explain plan
  2  for
  3  select *
  4    from ( select empno
  5                , ename
  6                , sal
  7                , rownum rowno
  8             from emp
  9         )
10   where empno = 7839
11  /
Uitleg is gegeven.
SQL> select * from table(dbms_xplan.display)
  2  /
PLAN_TABLE_OUTPUT
Plan hash value: 2077119879
| Id  | Operation           | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT    |      |    14 |   644 |     3   (0)| 00:00:01 |
|*  1 |  VIEW               |      |    14 |   644 |     3   (0)| 00:00:01 |
|   2 |   COUNT             |      |       |       |            |          |
|   3 |    TABLE ACCESS FULL| EMP  |    14 |   196 |     3   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter("EMPNO"=7839)
15 rijen zijn geselecteerd.
SQL> exec dbms_lock.sleep(1)
PL/SQL-procedure is geslaagd.
SQL> explain plan
  2  for
  3  select *
  4    from ( select empno
  5                , ename
  6                , sal
  7                , rownum rowno
  8             from emp
  9            where empno = 7839
10         )
11  /
Uitleg is gegeven.
SQL> select * from table(dbms_xplan.display)
  2  /
PLAN_TABLE_OUTPUT
Plan hash value: 1054641936
| Id  | Operation                     | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT              |        |     1 |    46 |     1   (0)| 00:00:01 |
|   1 |  VIEW                         |        |     1 |    46 |     1   (0)| 00:00:01 |
|   2 |   COUNT                       |        |       |       |            |          |
|   3 |    TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    14 |     1   (0)| 00:00:01 |
|*  4 |     INDEX UNIQUE SCAN         | EMP_PK |     1 |       |     0   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   4 - access("EMPNO"=7839)
16 rijen zijn geselecteerd.Now the two queries are not the same anymore. If you wonder why, please look carefully at the query results of both:
SQL> select *
  2    from ( select empno
  3                , ename
  4                , sal
  5                , rownum rowno
  6             from emp
  7         )
  8   where empno = 7839
  9  /
     EMPNO ENAME             SAL      ROWNO
      7839 KING             5000          9
1 rij is geselecteerd.
SQL> select *
  2    from ( select empno
  3                , ename
  4                , sal
  5                , rownum rowno
  6             from emp
  7            where empno = 7839
  8         )
  9  /
     EMPNO ENAME             SAL      ROWNO
      7839 KING             5000          1
1 rij is geselecteerd.Regards,
Rob.