The siblings already said it, but event sourcing requires you (at least for practical purposes) to segregate the read model from the write model using "projecti

The siblings already said it, but event sourcing requires you (at least for practical purposes) to segregate the read model from the write model using "projections". The good thing is that, whenever you create a new service, you can derive the projections that your service will need from the same source of truth. In this way, you create coupling on the data, but not on the concrete service that owns it. This is not very different from what a relational database does with redo logs. In fact, in a way, using event sourcing resembles composing a system from the fundamental building blocks of a traditional DBMS, in a distributed way.