Going Transactionless - Scalable Data Tiers

Dan Pritchett posted his excellent "How eBay Scales" presentation a few months back.

It is a great look into a real-world massive distributed system and the evolution of its scalable architecture.  One interesting thing to notice is that eBay is a transactionless environment (meaning it doesn't use Database Transactions).

I have always seen the data layer as the difficult part to scale.  Separating logic from data and working in a purely transactionless environment can mitigate this issue.

Martin fowler commented on this today:

"The rationale for not using transactions was that they harm performance at the sort of scale that eBay deals with. This effect is exacerbated by the fact that eBay heavily partitions its data into many, many physical databases. As a result using transactions would mean using distributed transactions, which is a common thing to be wary of.

This heavy partitioning, and the database's central role in performance issues, means that eBay doesn't use many other database facilities. Referential integrity and sorting are done in application code. There's hardly any triggers or stored procedures."