Tungsten

It seems there is a fork of the old C-JDBC project that I was not aware of:

Tungsten is an open source stack for deploying and operating horizontally scaled database clusters, also known as database scale-out. Scale-out works by spreading data across multiple, independent database servers connected through a network. The model offers an intuitive, incremental approach to solving the following important database problems:

• Preventing data loss though up-to-date replica databases and coordinated backups
• Increasing overall application availability by providing rapid database failover
  
• Raising performance and through-put by dispatching read traffic to replicas
• Integrating data between heterogenous systems, for example to support scaling of commercial databases using low-cost open source databases.

C-JDBC is:

an open source (LGPL) database cluster middleware that allows any Java application (standalone application, servlet or EJB container, ...) to transparently access a cluster of databases through JDBC(tm). The database is distributed and replicated among several nodes and C-JDBC balances the queries among these nodes. C-JDBC handles node failures and provides support for checkpointing and hot recovery.