Object space versioning

Often, the state of a database or object space needs to be conserved in order to access earlier versions of the data. In order to support consistent versioning, ODABA allows defining object space versions (version slices). Within a time interval (version slice) all modifications of the objects are treated as "corrections". Starting a new object space version, new versions of object instances are created whenever the object instance is modified. The version interval can be a fixed interval (e.g. each hour, weekly or monthly, yearly) or a variable interval explicitly defined by the database administrator.

The version creates a new dimension for the database, which should not affect the data model at all.

ODABA supports a differential version control which allows to create up to 65535 versions for an object space (beginning a new version each day, versions for 180 years could be created for an object space). In a database supporting full version control each version reflects a consistent state of the database at a certain time, not only for the instances but also for the relationships between them, as well as for indexes .

There are two versioning modes supported for object space versioning:

• object versioning
• consistent versioning