SQL Optimization with join and in subselect

Question

Hello,
I am having problems finding a way to optimize a query that has a join from a fact table to several dimension tables (star schema) and a constraint defined as an in (select ....). I am hoping that this constraint will filter the fact table then perform the joins but I am seeing just the opposite with the optimizer joining first and then filtering at the very end. I am using the cost optimizer and saw that it does in subselects last in the predicate order. I tried the push_subq hint with no success.
Does anyone have any other suggestions?
Thanks in advance,
David
example sql:
select ....
from fact, dim1, dim2, .... dim <n>
where
fact.dim1_fk in ( select pf from dim1 where code = '10' )
and fact.dim1_fk = dim1.pk
and fact.dim2_fk = dim2.pk
and fact.dim<n>_fk = dim<n>.pk

Answer 1

The original query probably shouldn't use the IN clause because in this example it is not necessary. There is no limit on the values returned if a sub-select is used, the limit is only an issue with hard coded literals like
.. in (1, 2, 3, 4 ...)Something like this is okay even in 8.1.7
SQL> select count(*) from all_objects
  2  where object_id in
  3    (select object_id from all_objects);
  COUNT(*)
     32378The IN clause has its uses and performs better than EXISTS in some conditions. Blanket statements to avoid IN and use EXISTS instead are just nonsense.
Martin