Orphan records can pose serious problem in an operational or OLTP database. However, they are less of an issue in a data warehouse. There is this thing called "late arriving dimensions", where fact records arrive coded with things like Customer IDs or Product IDs that havn't been loaded yet. In a DW where reports are released periodically and most user interaction is in the form of ad-hoc queries, orphan records are more of a nuisance or known issue that gets resolved shortly with a followup data load.