[_3u10]

Pretty much. Also all your projectors need to be deterministic.

eg. Your commands have to ALWAYS do the same thing else replaying the event log does not produce the same output and then you’re back to square one.

It’s usually easier / more useful to just use an audit table.

[blowski]

Yes, if version 1.3 of Command handler X was the active version when an event happened, then it needs to be replayed with that version, even if you’re now on v4.5.