eventual-consistency

I am in the early stages of design of an application that has to be highly available and scalable. I want to use an eventual consistency data model for this for a number of reasons. I know and understand why this is an unpopular architectural choice for many solutions, but it's important in my case. I am looking for real-world advice, best-practices and gotchas to look out for when dealing with distributed / document-style databases. And particularly areas around e-commerce (shopping cart style) apps that traditionally are easier to put together with a relational db. I understand using these

I have a fairly simple domain model involving a list of Facility aggregate roots. Given that I'm using CQRS and an event-bus to handle events raised from the domain, how could you handle validation on sets? For example, say I have the following requirement: Facility 's must have a unique name. Since I'm using an eventually consistent database on the query side, the data in it is not guaranteed to be accurate at the time the event processesor processes the event. For example, a FacilityCreatedEvent is in the query database event processing queue waiting to be processed and written into the