Patent ID: 6560601
Filing Date: 2003-05-06
Classification: G06F,Y10S

Abstract:
A method of providing consistent reading of a number of objects within a database, wherein a database transactions is managed by locking in two phases, wherein a first phase includes a request for access to objects affected by said transaction and locking of said objects after access thereto has been obtained, wherein a second phase includes committing said transaction, and wherein all locks set in said first phase are released, wherein an actual work carried out by said transaction can include object-changing actions and/or object non-changing actions, wherein a change in the content of an object, or updating of said object, is effected by said transaction writing a new content into a new version of said object, wherein the current version of said object prior to said transaction is retained until no further transactions make use of said current version, and wherein said transaction performs all changing actions in said first phase, characterised in that said transaction retains said access for reading concerned object versions after said second phase, said access to an object after said second phase consists in marking the current versions of respective object as being used by said transaction, in that said transaction carries out the largest possible number of non-changing actions after said second phase; and in that said transaction closes the access to said objects after performing said non-changing actions, where closing of a transaction consists in erasing said mark, whereby said method provides a consistent snapshot of affected objects within said database after the release of said locks.