Appeal No. 2002-1950 Page 2
Application No. 09/234,514
managed by two-phase locking." (Id.) A first phase (A) includes requesting access to
objects affected by a transaction and locking the objects when the request is granted.
A second phase (B) includes committing the transaction and releasing all locks
that were set in the first phase. The work done in a transaction may be a changing
action or a non-changing action. For a changing action, the content of an object is
changed by writing new content into a new version of the object, where the version of
the object existing before the transaction is retained until no further transactions use it.
Although all changing actions are done within the first phase, the transaction retains
access to the objects after the second phase and performs the largest possible number
of non-changing actions in a third phase, after which the transaction closes access to
the objects. (Id.) Consequently, asserts the appellant, the invention provides "the
transaction is provided with a consistent snapshot of effected objects . . . in the
database," (id.), "therewith enabling the transaction to use the consistent picture of the
object[s] for non-changing actions without limiting the transaction with respect to time
and without blocking other transactions." (Id. at 9.)
A further understanding of the invention can be achieved by reading the following
claim.
24. A method of providing consistent reading of a number of
objects within a database comprising the steps of:
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