I want to create and implement a Data Vault Model. In the presentation layer, I want to create a View based on a star schema. Now I would like to know if there is a certain order in creating the models in practice? (Is is a commonplace to create first a Data Vault model and then the star schema, or vice versa?) I noticed that I think very "dimensional" when start to make a concept of the requirements.

One of the key components of designing a data vault is identifying **enterprise-wide unique business keys** ("business key" AKA "natural key"). It's not enough to use OrderID to identify records in an Orders table, because when you add another orders table from another source system (e.g., a brick-and-mortar store launches an online store), there may well be collisions. In Data Vault best practices, should one include the name of the source system as one of the fields used to uniquely identify a record, when adding it to a hub table? Rather than searching for some combination of fields in Orders which will *hopefully* be universally unique ({ CustomerID, OrderID, and OrderDate }, maybe), one could identify brick-and-mortar orders with { "Brick-and-Mortar Order System", OrderID }, and one could identify online orders with { "Online Order System", OrderID }: This seems like the obvious solution, but I've not seen it mentioned in any of the Data Vault modeling documents I've found, so I wonder if there's some reason not to use this approach. The Data Vault approach seems to be an outgrowth of Master Data Management practices, so if this is a solved problem in MDM, that solution probably applies here too.

I'm learning about the Data Vault data warehousing approach, and so far the examples I've seen have a DateLoaded or similar field in all tables (hub, link, and satellite), but a DateExpired or EndDate field only in satellite tables. If a relationship is deleted in a source system, should this be recorded only by setting the DateExpired field in the link's satellite table(s), or should one also maintain a DateDeleted field in the link table? Note that I'm asking about "better" from a "Data Vault best practices" perspective. For a specific application there may be good reasons to favor one approach or the other.