Hi Molong,

An implementation of JanusGraph backend storage for RDBMS is available at https://github.com/mneethiraj/janusgraph/tree/rdbms_backend. The implementation uses EclipseLink JPA to access RDBMS, which enables support for large number of database flavors – including Postgres, MySQL, Oracle, MS-SQL. A brief document on RDBMS storage backend configuration is available here. I tested with Postgres, it works well; and should work with other RDBMS flavors supported by EclipseLink as well.

Hope you find this useful.

Madhan