The Lambda Architecture is pretty well documented – online1 as well as in the book I just mentioned2. For a quick overview, Lambda Architecture is basically a system where the raw data is always stored, and never thrown away. All information that’s derived from this raw data is always recomputed – often stated as query = function(all data). This provides for a fool-proof architecture that’s rigorously simple (compared to classic RDBMS solutions), made up of three layers:
Admittedly, about half of this went over my head, but there are some good book and webpage recommendations to learn more about lambda architecture and Data Vault.