Whenever I read mention of Neptune, I feel obligated to mention Blazegraph, which Amazon based Neptune on.
As I've shamelessly advertised elsewhere in these comments, Blazegraph is in the early stages of a fork and/or reboot, as Amazon's acquisition severely hampered progress on the open source project.
As I've shamelessly advertised elsewhere in these comments, Blazegraph is in the early stages of a fork and/or reboot, as Amazon's acquisition severely hampered progress on the open source project.
https://github.com/blazegraph/database/issues/86