The REPL 56: XTDB: A Bitemporal database in Clojure
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Jun 13, 2025 
Join Jeremy Taylor, Head of Product at Juxt and a bitemporal database expert, and James Henderson, Head of Engineering, as they dive into the fascinating world of XTDB. They discuss the importance of bitemporality for accurate historical data in finance, the evolution of XTDB and its SQL compatibility goals, and how industry tools like Kafka enhance durability. Insights on architecture, including Apache Arrow use, indexing trade-offs, and the role of shared concepts set the stage for a robust understanding of modern databases.
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Bitemporality Makes Accurate Reporting Trivial
- XTDB makes bitemporality intuitive by keeping full history so reports reflect "what was known" at any time.
- Jeremy Taylor argues this reduces ad-hoc user-space fixes and proliferation of separate analytics systems.
Make Adoption Low Friction
- Use Postgres wire compatibility to lower adoption friction for non-Clojure teams.
- Jeremy Taylor recommends exposing SQL so analysts and data engineers can use familiar tools.
Energy Marketplace Example
- A design partner built an energy marketplace using XTDB to track sensor voltages and a dynamic network graph.
- Regulators required precise historical views so XTDB's bitemporality matched the domain's historian systems.