If you want invalid states unrepresentable, and time as a primary key... How do you deal with time regularly becoming non-linear within the realm of computing?
Then each event is associated with zero or more "parent events".
- An event has 0 parents if it is the first change
- An event has 1 parent if it simply came after that event in sequence
- And if an event merges 2 or more branches in history, it says it comes after all of those events
You can also think about it like a set. If I know about events {A, B, C} and generate event D, then D happens-after {A, B, C}. (Written {A,B,C} -> D). But if A->B, then I only need to explicitly record that {B,C} -> D because the relationship is transitive. A -> B -> D implies A -> D.
There are techniques to make it less painful, but it will still be possible.
There may be a way to solve whatever problem you have, but without specifics it’s impossible to tell.
Einstein just had to come along and screw everything up.
Causality is the key.