FlockDB was a distributed, fault-tolerant graph database.
Twitter announced in 2017 that the project was no longer being maintained. It has since moved to an 'archive' repository on Github.
Graph
https://github.com/twitter/flockdb
https://github.com/twitter-archive/flockdb
Twitter
US
2010
2017
Open Source
Scala
MySQL
Apache v2
https://en.wikipedia.org/wiki/FlockDB