We've tried Neo4J, ArangoDB, as well as many others to store the triples. Neo4J locked up at around 100M entities, and also the loading/injection times weren't sufficient build the KG at a regular interval. However, we are closely following any developments in these projects as they improve. There is more detail in this interview here: https://www.zdnet.com/article/the-web-as-a-database-the-bigg...