will DB2 use the index for a SQL like this?
i have an index on the A table like this +ORD_NBR+LD_STP_NBR
+REC_STT

Select .....
from .....
where .....

OR ((A.ORD_NBR , A.LD_STP_NBR) IN

( SELECT AA.ORD_NBR, B.LD_STP_NBR From........)

You can check by yourself using explain functionalities of DB2.