Let’s have a look at Greenplum Database Single-Node Edition.
This new, free version of Greenplum Database gives data analysts access to Greenplum’s high-performance database for large-scale analytical projects outside the enterprise data warehouse (EDW). The Single-Node Edition is a state-of-the-art parallel analytic database
It’s free for up to 2 CPU sockets (unlimited cores), and supposedly good for 50TB and more (eBay hosting 60TB on each of their Greenplum nodes). Other goodies are SSD support built-in, hybrid row and column-oriented processing, and the ability to grow the free install to a cluster. The cluster appears to be shared nothing, like DB Sharding.