With hashing, a record can be located efficiently by first applying the hash
function and, if a collision has occurred, using one of these approaches to locate
its new address. To update a hashed record, the record first has to be located. If
the field to be updated is not the hash key, the update can take place and the
record written back to the same slot. However, if the hash field is being updated,
the hash function has to be applied to the new value. If a new hash address is
generated, the record has to be deleted from its current slot and stored at its new
address.