Inspired by Felix Geisendorfer blog post I implemented a database FSM (Finite-State Machine) with Postgresql. I brought some improvements to Felix’s implementation but before reading the following I recommend you to read carefully the original post. TL;DR Here are the changes I did: Introduced a versioning control of the FSM. Optimized performances and data storage. Added some protection against user mistakes To keep it simple I’ll use exactly the same FSM graph than Felix: an ordering process w...