XTDB is a general purpose database with graph-oriented bitemporal indexes. Datalog, SQL & EQL queries are supported, and Java, HTTP & Clojure APIs are provided.

XTDB follows an unbundled architectural approach, which means that it is assembled from decoupled components through the use of an immutable log and document store at the core of its design. A range of storage options are available for embedded usage and cloud native scaling.

Bitemporal indexing of schemaless documents enables broad possibilities for creating layered extensions on top, such as to add additional transaction, query, and schema capabilities. In addition to SQL, XTDB supplies a Datalog query interface that can be used to express complex joins and recursive graph traversals.

https://github.com/xtdb/xtdb

https://www.xtdb.com/learn