How to optimize this query?

Greetings,

I have this query:

select some field from tbl where flag1=0 and flag2=1 and flag3=2 and flag4=3 and flag5=4

flag1, flag2 and flag3 are all checked in (0,1,2,3,4,5).

And I have a index on flag1, flag2 and flag3 since flag4 and flag5 in more case are constants(3 and 4).

When tbl has huge number of data (over a half million records), I find that if tbl contains data meet query condition, the select performs well. But if not, the select cosumes huge resource.

Do you have any idea to optimize this kind of query? I am using Oracle 8.1.5.

Thanks in advance!
Evan Received on Mon Aug 04 2003 - 22:03:50 CDT