When oracle invalidates result_cache results without any changes in objects

Question

Hi all!
On our production servers we have simple function with result_cache, like this:
create or replace function f_rc(p_id number) return number result_cache
is
  ret number;
begin
  select t.val into ret from rc_table t where t.id=p_id;
  return ret;
exception
  when no_data_found then
     return null;
end;
/And its results frequently invalidates without any changes in table or
function. I found only 2 cases when oracle invalidates result_cache
results without any changes in table:
1. "select for update" from this table with commit;
2. deletion of unrelated rows from parent table if there is unindexed
foreign key with "on delete cascade".
I test it on 11.2.0.1, 11.2.0.3, on solaris x64 and windows. Test
cases: http://www.xt-r.com/2012/07/when-oracle-invalidates-resultcache.html
But none of them can be the cause of our situation: we have no
unindexed fk, and even if i lock all rows with "select for update", it
still does not stop invalidating.
In what other cases this happens? Am I right that the oracle does not
track any changes, but the captures of the locks and "commits"?
Best regards,
Sayan Malakshinov
http://xt-r.com

Answer 1

Hmm.. Do you about our situation or about test cases with "select for update" and "fk" too?
I'm not sure that it is a bug, maybe it's an architectural approach to simplify and reduce the cpu load?
Best regards,
Sayan Malakshinov
http://xt-r.com