GraphDB from Ontotext is a native RDF database with dynamic indexing that integrates with various search technologies (most notably Elastic Search), document stores (MongoDB), as well as text mining.
Where we particularly like Ontotext is in the care it takes when implementing new features and capabilities. For example, it is the best implementation of RDF* that we have seen, while the scope of the Ontotext Platform is broader than anything else in the market. The company seems to have thought more deeply about all the things that you might need in a graph environment, than other suppliers. We also like the extended capabilities it offers within its Platform, its support for GraphQL to make development simpler, and the integration with open source technologies of various kinds.