Thanks for your reply..I am actually doing what you are saying..here is the complete code:

INDEX ON BINTOC(SIL_INV_FK) + BINTOC(SIL_INV_CFK) TAG SILMAIN
SET ORDER TO SILMAIN
COPY TO v_InventoryTemp FOR BINTOC(SIL_INV_FK) + BINTOC(SIL_INV_CFK) == BINTOC(tnINVPK) + BINTOC(tnINVCPK)

where tnINVPK/CPK contain the correct values at runtime. COPY TO *is* giving me the correct records, but its performance seems very, very poor compared to that of the SELECT command.