xtdb/xtdb

XTDB is an immutable SQL database that provides comprehensive time-travel capabilities for application development, time-travel reporting, and data compliance.

XTDB addresses the challenge of maintaining complete data history and handling complex temporal requirements without snapshots or backup restoration. It implements bitemporal versioning, which tracks both system time (when updates occur) and valid time (when data is, was, or will be valid in the business domain). The database is optimized for current-time queries while allowing full audit trails of historical states. It uses an immutable, columnar architecture built on Apache Arrow and designed for object storage, with a log-centric coordination model for distributed deployments.

The tool suits applications requiring strict data compliance, audit trails, or complex temporal queries. Its dynamic schema allows documents with arbitrarily nested data to be inserted without upfront schema definition. XTDB exposes both SQL and XTQL, a full SQL dialect implementing bitemporal functionality as specified in the SQL:2011 standard, available over the Postgres wire protocol. This makes it accessible to teams familiar with standard SQL tooling while providing specialized temporal query capabilities.

The project maintains active engagement with its community through GitHub Discussions and a Discord community. Development activity shows consistent attention to documentation and release management, with organized development resources and a maintained bibliography of related research. The codebase is written in Clojure and supported by JUXT, the organization behind the project.