You cannot drop a join index to enable batch data loading by utilities such as MultiLoad and FastLoad as long as queries are running that access that join index. Each such query places a READ lock on the join index while it is running, so it blocks the completion of any DROP JOIN INDEX transaction until the READ lock is removed. Furthermore, as long as a DROP JOIN INDEX transaction is running, batch data loading jobs against the underlying tables of the join index cannot begin processing because of the EXCLUSIVE lock DROP JOIN INDEX places on the base table set that defines the index.