Is oracle can do this

Question

Hi,
i have a view that is doing uinion all with 3 tables.
this view is big and results are about 80 milions rows.
i'm selecting from this view and filtering base on another very small table (only 5 rows)
oracle is not able to filter the rows in the view ( push it down inside the view)
it is doing the hash and building the view and after it doing the filter.
when i change the subquery to hardcoded values then i's doing the pushing .
here is an example :
this is the view
create view z1_abc as
select 'a' tbl,a.* from z1_a a
union all
select 'b' tbl,b.* from z1_b b
union all
select 'c' tbl,c.* from z1_c c
my query :
select * from z1_abc
where id in (select id_f from z1_f)
**** this one not able to filter the values in the view*
second query :
select * from z1_abc
where z1_abc.id in (1,2,3,8)
this query is ok ( ofcourse )
my question :
is it possible to use some dynamic filter but also to benfit from filter inside the view ?
10x
Zvika

Answer 1

10x
i also tried the join and push predicate methods with no success ..
the CBO still doing the union all and after it it filter the subquery or doing the join.
in my real query the union all is more complex with joins in every block of the union all query.
so i want to reduce the join cardinality as much as i can .
here is the explain plan :
join and subquery the same
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 2 | 38 | 9 |
|* 1 | HASH JOIN SEMI | | 2 | 38 | 9 |
| 2 | VIEW | Z1_ABC | 9 | 144 | 6 |
| 3 | UNION-ALL | | | | |
| 4 | TABLE ACCESS FULL| Z1_A | 3 | 9 | 2 |
| 5 | TABLE ACCESS FULL| Z1_B | 3 | 9 | 2 |
| 6 | TABLE ACCESS FULL| Z1_C | 3 | 9 | 2 |
| 7 | TABLE ACCESS FULL | Z1_F | 4 | 12 | 2 |
Predicate Information (identified by operation id):
1 - access("ID"="ID_F")
and when using hard coded values
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 9 | 144 | 6 |
| 1 | VIEW | Z1_ABC | 9 | 144 | 6 |
| 2 | UNION-ALL | | | | |
|* 3 | TABLE ACCESS FULL| Z1_A | 3 | 9 | 2 |
|* 4 | TABLE ACCESS FULL| Z1_B | 3 | 9 | 2 |
|* 5 | TABLE ACCESS FULL| Z1_C | 3 | 9 | 2 |
Predicate Information (identified by operation id):
3 - filter("A"."ID"=1 OR "A"."ID"=2 OR "A"."ID"=3 OR "A"."ID"=8)
4 - filter("B"."ID_B"=1 OR "B"."ID_B"=2 OR "B"."ID_B"=3 OR
"B"."ID_B"=8)
5 - filter("C"."ID_C"=1 OR "C"."ID_C"=2 OR "C"."ID_C"=3 OR
"C"."ID_C"=8)
Zvika