In the example that you gave, you used a transaction as an example of a case
where you needed the historical data (e.g. address) This is an example of a
common areas where this is needed. If this is the main need, you might want
to start databasing the entire transaction events (e.g. invoices, e.g.
including the at-the-time billing address) as entities. (vs. treating only
certain items in them as entities, and "deriving" the invoice each time that
it is printed.)