CockroachDB

CockroachDB is a distributed SQL database for building, scaling and managing data-intensive modern applications. It is layered on a transactional, strongly consistent key-value store and offers a familiar SQL API for defining, changing and querying data, with ACID transactions across the cluster.

It scales horizontally by adding nodes and is designed to keep running through failed disks, machines, racks and even whole datacenters, with little added latency and no manual recovery. Control over where data is placed is part of the pitch, which matters for locality and compliance. Documentation covers installation, development, deployment and administration, client drivers, and a comparison with other databases, and the design is explained in a public architecture document.

CockroachDB is written in Go. Its license is listed as 'Other' on GitHub, so review the current license terms before using it commercially. You can run your own cluster or let Cockroach Labs run it as the managed CockroachDB Cloud service. It suits teams that need resilient, multi-region relational storage without sharding by hand.