XTDB is an immutable database implemented in Clojure. Inspired by Datomic, but a different animal. Launched in 2019, it's bitemporal and documentbased, built with the 'database insideout' mantra of exposing internal components as swappable parts.

We've learned a lot, first and foremost that building a database is hard! Clojure has been a true superweapon, allowing us to iterate quickly and prototype new approaches with ease. It's what's made this epic task building something as complex as a database with a small dedicated team actually possible.

XTDB is evolving. We've been proving concepts through a research project codenamed "Core 2" (https://www.xtdb.com/v2), with a new query engine, new storage mode, and more powerful temporal functionality. Our goal is to advance XTDB, given all that we've learned, and to make a database that gives users new fundamental capabilities.

In the talk I'll reflect on what we've learned so far building XTDB, and where we're taking XTDB next.