In a client-server system with page shipping, when a client requests an item, the server typically grants a lock not on the requested item, but on the page having the item, thus implicitly granting locks on all the items in the page. The other items in the page are SAID to be prefetched. If some other client subsequently requests one of the prefetched items, the server may ask the OWNER of the page lock to transfer back the lock on this item. If the page lock owner doesn’t need this item, it de-escalates the page lock that it holds, to item locks on all the items that it is actually accessing, and then returns the locks on the unwanted items. The server can then grant the latter lock request. If the unit of data shipping is an item, there are no COARSER granularity locks; even if prefetching is used, it is typically implemented by granting individual locks on each of the prefetched items. Thus when the server asks for a return of a lock, there is no question of de-escalation, the requested lock is just RETURNED if the client has no USE for it.

In a client-server system with page shipping, when a client requests an item, the server typically grants a lock not on the requested item, but on the page having the item, thus implicitly granting locks on all the items in the page. The other items in the page are said to be prefetched. If some other client subsequently requests one of the prefetched items, the server may ask the owner of the page lock to transfer back the lock on this item. If the page lock owner doesn’t need this item, it de-escalates the page lock that it holds, to item locks on all the items that it is actually accessing, and then returns the locks on the unwanted items. The server can then grant the latter lock request. If the unit of data shipping is an item, there are no coarser granularity locks; even if prefetching is used, it is typically implemented by granting individual locks on each of the prefetched items. Thus when the server asks for a return of a lock, there is no question of de-escalation, the requested lock is just returned if the client has no use for it.