A method is described for managing an application's cached persistent data
with different isolation levels. The different isolation levels include:
1) requesting a lock for a first item of database data in response to the
first item of database data not being cached and not yet having been used
by the application; 2) requesting a lock for a second item of cached
database data in response to the second item of database data being
updated for a first time by the application; and, 3) requesting a lock
for a third item of cached database data in response to it being
confirmed that the third item of database data will need to be updated in
its database.