Tamil, thank you! I was afraid of it would check rpo_key, vehicle_key one by one or any of them instead of checking the pair! I need to guarantee the pair of rpo_key, vehicle_key to be unique.
Is there a way to verify the script would check the pair of rpo_key, vehicle_key not in vmap table before the new data get into vmap_temp table?

No, I didn't check (rpo_key, vehicle_key) uniqueness in the temp table?

Thanks again!