Since we are using separate database any
failure that might cause the database to corrupt
is now limited only to the registration database,
leavingt he centrald atabase untouched. F or the
case that registration database is collapsed, it
can easily be reconstructed within three
minutes, since it contains only information for
registration it is then ready to be used again to
provide uninterrupted service during the
registration period. Furthermore, for any
terminated transaction the transactionm anager
is used to provide the atomicity of important
transactions. In other words, it guaranteetsh at
if the transactione xecutess ome updatesa nd a
failure occurs (whatever the cause) before the
transactionfi nishes( reachi ts plan), then those
updates will be undone. Thus, the transaction
either executes in its entirety or is totally
canceled.I n this way a sequenceo f operations
that is fundamentally non-atomic can be viewed
as if it were atomic from this point of view. The
commit transaction and rollback transaction are
the key to the way recovery works. For commit
transaction,it tells the DatabaseM anagement
System (DBMS) that the atomicity of the
process has been thoroughly finished. The
database is in a consistenst tatea nd the updates
made by the process can now be made