Foreign Keys

If a dataset contains one or more fields that together can be used to identify a resource in another dataset, or even another instance of the same resource, those fields taken together make up a “foreign key.” Foreign keys consist of the following:

• The field or fields in the source dataset that make up the key

• The target dataset that links to the key

• The fields in the destination dataset that match up to the fields in the source dataset

When a foreign key exists in a dataset, the Observe user interface displays a link to follow the key relationship to the target dataset. You can also use foreign keys to lookup values from the target dataset by browsing the relations.

Related Keys

When some other dataset points into a dataset, that target dataset is also related to the other dataset. That relationship is called a “related key” with a “what links here” relationship. This is not generally a foreign key, because many remote resources may link to a single resource instance. For example, a single host may have multiple disks in it and if you follow this related key, you may end up finding multiple remote resources for a single source resource.