Resolution of relationship source and target in a versioned database management system

摘要

A versioned data management system is provided with a method for resolving sources and targets of relationships. For each entity instance, a lifetime ID is recorded. When the add interface is used to add an entity, a value is assigned to the lifetime ID, which value has never been used before for an instance of the entity type. When the update interface is used to update an entity, the lifetime ID is maintained unchanged. If the update results in a new version, the new version is given the same lifetime ID value as that for the version that was the basis for the update. If the delete interface is then used to delete the entity, and the add interface is later used to add an instance with the same part key, that instance will have a different lifetime ID. For each relationship instance, lifetime IDs are recorded for the relationship, its source, and its target. When the add interface is used to add a relationship, a value is assigned to the lifetime ID, which value has never been used before for an instance of the relationship type. Also, the lifetime IDs of the source and target of the relationship are recorded in the relationship instance. The lifetime ID of the relationship and the lifetime IDs of the source and target are maintained unchanged. If an update results in a new version of the relationship, the new version is given the same lifetime ID value as that for the version that was the basis for the update.