I'm considering to use JDBC-compliant driver with JDO to connecto to Cassandra. Is this possible and is this going to cause huge overhead? I was looking astyanax made by Netflix, and it looks good, but it is not easy as JDO seems to be.
If using a JDBC driver you need to write an RDBMS adapter class for Cassandra to communicate with it (see the DN docs).
Alternatively use a Cassandra plugin for DataNucleus https://github.com/pulasthi/Datanucleus-Cassandra-Plugin Note that this plugin was not provided by the DataNucleus project (so some things in it may be non-optimal due the people concerned not necessarily understanding how a store plugin ought to be written) and only works for DataNucleus v2.x.
Update [Jan 2014] : there is now an official DataNucleus Cassandra plugin under development, already providing many things, and using CQL3