Which record a stage is working on. Before it is persisted the identity is its URL (Discover's stable identity for what it found); once a primary key exists, that is used instead. The URL is kept so a re-discovery can match the existing row.
The durable primary key once committed; null before.
null
Readonly
True once this record has a durable primary key.
The real key when there is one, the URL otherwise.
Which record a stage is working on. Before it is persisted the identity is its URL (Discover's stable identity for what it found); once a primary key exists, that is used instead. The URL is kept so a re-discovery can match the existing row.