title: How do you ensure that events are applied in order to read model?
body: <p>This is easy for projections that subscribe to all events from the stream, you just keep version of the last event applied on your read model. But what do you do when projection is composite of multiple streams? Do you keep version of each stream that is partaking in the projection. But then what about the gaps, if you are not subscribing to all events? At most you can assert that version is greater than the last one. How do others deal with this?  Do you respond to every event and bump up version(s)?</p>