Cannot Load Index Into Keep Pool

Question

I've sucessfully loaded my ctxsys.context index into the keep pool (works great) using the web page: http://www.oracle.com/technology/products/text/htdocs/mem_load.html .
I'm now trying the techniques to load a regular index (that joins to my text index).
I've executed:
alter index PROD_SVC_NDX storage (buffer_pool keep);
Then I tried the hint INDEX_FFS on the base table:
select /*+ INDEX_FFS ( INDEXDATA , PROD_SVC_NDX ) */ count(svc_code) FROM INDEXDATA ;
The optimizer shows a ffs in the algorithm:
INDEX FAST FULL SCAN| PROD_SVC_NDX |524K| 2047K|251 (2)| 0:00:04
WHEN I QUERY THE BUFFER CACHE, only 9% of the index is in the keep pool..
Owner............. Name...........................Type...........Cache....... %BLOCKS........POOL........BSize
SYSTEM.......PROD_SVC_NDX...........INDEX..........1,248.................9..............KEEP.........8,192.
How do you load regular index blocks into keep pool?
What would be the best Oracle forum for this question?
Joe

Answer 1

I think the optimizer will always use a full scan for such a query, regardless of hints. What you need to do is fetch all rows individually. This can be done in a PL/SQL block with an outer loop which fetches all the indexed values, and an inner select that performs an indexed lookup with each value. For example:
Given a table with a primary key index:
create table foo (pk number primary key, bar varchar2);
Populated:
insert into foo values (1, 'aa');
insert into foo values (2, 'ab');
insert into foo values (3, 'ac');
We could do this:
declare
v_bar varchar2(2);
begin
for q in (select pk from foo) loop
select bar into v_bar from foo where pk = q.pk;
end loop;
end;
It may well not be necessary to fetch every row - you should experiment and see whether maybe fetching every 10th row - or even every 100th row - is sufficient to fetch all index blocks into the SGA.
- Roger