Datomic

Datomic is a distributed database that emphasizes immutability, scalable reads, and time-based queries. It was created by Rich Hickey and Cognitect and was first released in the early 2010s. The core data model stores facts as datoms, four-element records consisting of an entity, an attribute, a value, and a transaction instant. All datoms are immutable; new facts are added through transactions, and historical datoms remain to support queries about the past. Datomic provides time-aware queries by projecting the database’s history at any point in time.

Queries are expressed in Datalog, a declarative logic language, and Datomic offers convenience operations such as pull for nested data and temporal queries over database value snapshots. The system separates the write path from the read path using a transactor and a durable storage layer. The transactor accepts transactions and appends datoms to storage, while clients query against a database value that reflects a consistent view of datoms up to a chosen time.

Datomic is available in multiple editions, historically including Datomic Free, Datomic Pro, and Datomic Cloud, with deployment modes such as On-Prem or Cloud. Cloud Edition accesses managed storage in the cloud; On-Prem runs in customer-controlled infrastructure.

The product has been associated with Cognitect, which was acquired by Nubank, and Datomic continues to be offered as a vendor-supported database for applications requiring strong consistency, historical auditing, and rich relational querying without the need for traditional ETL to enable time travel.