[piaste]

> There is no world where it makes more sense to write a copy of everything you do into an "everything I did" table, than it does to use an append-only / immutable / log-centric DBMS (where "Postgres with an ETL pipeline pointed at its WAL logs" is a rather hacky immutable DBMS.)

There is one: the world where append-only / immutable / log-centric DBMS do not offer the same advantages as mainstream RDBMSs - scalability, stability, performance, language support, open sourcing, active development, ubiquitous SQL knowledge, etc. etc.

The downside of bolting an event-sourcing or changelog system onto an established RDBMS like Postgres are (a) the cost of writing them, and (b) the performance / disk space cost. Both of those may be easier to deal with than, say, Datomic's licensing and Clojure-oriented APIs, especially if you can use an existing library like Marten.

What immutable DBMS would you recommend?