> If ever you decide you want to migrate away from Postgres, you'll need to rewrite all the business logic into some other out of process language.
Of you follow this rule you'll never be able to use the most powerful features of postgres.
> If ever you want to scale this, such that you want to calculate states in batches, you'd want to have the business logic somewhere else...
Not due I'm totally on board with the premise here, but the need to calculate state outside the database is a generally valid one and so it might be a good idea to write the core of the transition function in JavaScript and implement the postgres functions in PLv8.
Of you follow this rule you'll never be able to use the most powerful features of postgres.
> If ever you want to scale this, such that you want to calculate states in batches, you'd want to have the business logic somewhere else...
Not due I'm totally on board with the premise here, but the need to calculate state outside the database is a generally valid one and so it might be a good idea to write the core of the transition function in JavaScript and implement the postgres functions in PLv8.