XTDB “Core2”

XTDB Core2 aims to become the world's first general-purpose Immutable Database. Ultimately, Core2 will serve hybrid transactional-analytical workloads. Core2 is currently in active R&D with a functioning core.

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Strange Loop 2022

Try XTDB Core2

You can find more information at core2docs.xtdb.com, Core2's preliminary documentation.


Core2 is the product of many years' research. If you are a developer or researcher interested in Core2's background, you can read and download our Core2 bibliography on Zotero .


Core2 is not currently stable or intended for real-world evaluation. Please see the rest of the xtdb.com website for information on XTDB 1.x, our commercially-supported software for production use.

To understand the roadmap for Core2 you can follow our GitHub project board. For any other enquiries please contact us to arrange a conversation.

XTDB vs. XTDB Core2

Core2's objective is to take the key principles embodied in XTDB 1.x – immutability, schemaless records, and temporal querying – to a mainstream SQL audience.

XTDB 1.x Core2 Research Concept
Status Stable Experimental (pre-alpha)
Initial Stable Release 2019 TBD
Interface Java + edn Datalog SQL — PostgreSQL native drivers, JDBC
NewSQL — HTTP (planned), Arrow FlightSQL (planned)
Secondary Interface OpenAPI, Calcite SQL (read-only) Many secondary languages (Datalog, SPARQL, Gremlin, etc.) are possible
Execution Model Tuple-at-a-Time Sort-Merge Joins Vectorized Relational Algebra
Storage & Compute Coupled (nodes are full replicas) Separated (cost-effective scale out)
Storage Format Custom Key-Value encodings Columnar Apache Arrow
Bitemporal Querying Timeslice only ('as-of') SQL:2011 and beyond
Analytical Querying No Yes
Temporal Granularity Milliseconds Microseconds
Index Upgrades Full log replay Online
Transaction Log Infinite Retention Ephemeral WAL
Relational Decorrelation No Yes
Persistence Layer Transaction Log + Document Store Object Store

Ethos: Fully Open Source

JUXT holds a fundamental belief that any product we create must be fully open source and XTDB is no exception. We say "fully" because we do not consider "open core" products to be open source. Quality software speaks for itself and does not need to hide behind restrictive licenses.

All software has a lifespan. When closed-source software breathes its last, customers are left stranded. We consider this unethical. Your business should not be forced to accept the risk of closed-source software.

XTDB Core2 is licensed under the GNU Affero General Public License, v3. Commercial and Warranty licenses are available, where required.