XTDB is an open-source immutable database with comprehensive time-travel. XTDB has been built to simplify application development and address complex data compliance requirements. XTDB can be used via SQL and XTQL.

XTDB 2.x is in 'beta' whilst we collaborate closely with our Design Partners ahead of General Availability; if you are looking for a stable release of an immutable document database with bitemporal query capabilities, we are continuing to develop and support XTDB 1.x at https://github.com/xtdb/xtdb/tree/1.x.

Major features:

• Immutable - XTDB is optimised for current-time queries, but you can audit the full history of your database at any point, without needing snapshots or accessing backups.

• 'Bitemporal' - all data is accurately versioned as updates are made ('system' time), but it also allows you to separately record and query when that data is, was, or will become valid in your business domain ('valid' time).

• Dynamic - you don’t need to specify schema up-front before documents (rows with arbitrarily nested data) can be inserted.

• Speaks both SQL and XTQL - a full SQL dialect that implements the bitemporal functionality as specified in the SQL:2011 standard, available over both HTTP and the Postgres wire protocol for compatibility with existing experience and Postgres-related tooling.

• Cloud native - the ACID, columnar engine is built on Apache Arrow and designed for object storage

• It is written and supported by JUXT.

Quick links

• 2.x Documentation

• 1.x Documentation (see the 1.x branch)

• Maven releases

• Release notes

• Support: discuss.xtdb.com | hello@xtdb.com

• Developing XTDB 2.x

• Bibliography

Inside-out Architecture

XTDB embraces the transaction log as the central point of coordination when running as a distributed system.

What do we have to gain from turning the database inside out?

Simpler code, better scalability, better robustness, lower latency, and more flexibility for doing interesting things with data.

— Martin Kleppmann

XTDB 1.x

XTDB 1.x is a mature product offering that is used in production by many organizations, and its ongoing development is focused on hardening and performance. XTDB 1.x is an embeddable database that emphasizes in-process JVM usage to enable advanced functionality like user-defined transaction functions, speculative transactions, programmatic Datalog rules, and more.

XTDB 2.x’s initial objective is to take the key principles embodied in XTDB 1.x — immutability, schemaless records, and temporal querying — to a mainstream audience.

	XTDB 1.x	XTDB 2.x
Status	Stable	Beta
Initial Stable Release	2019	2024-2025
Query languages	EDN Datalog	XTQL + SQL:2011
Bitemporal Querying	Timeslice only (point-in-time)	Fully bitemporal - SQL:2011 and beyond
Query focus	OLTP	OLAP + OLTP ('HTAP')
Storage & Compute	Coupled (nodes are full replicas)	Separated (cost-effective scale out)
Primary Storage Format	Custom Key-Value encodings	Columnar Apache Arrow
-	-	-
Immutable Semantics	Yes	Yes
Online Transactions (ACID, strong consistency)	Yes	Yes
Always-On Bitemporality	Yes	Yes
Dynamism (ad-hoc graph joins, union typing, schemaless, etc.)	Yes	Yes

Questions, Thoughts & Feedback

We would love to hear from you: hello@xtdb.com

License and Copyright

XTDB is licensed under the Mozilla Public License, version 2 or (at your option) any later version.

Copyright © 2018-2024 JUXT LTD.