CarbonadoAs of today one of the technologies developed internally at Amazon is available on sourceforge as an open-source project. From the Carbonado docs:
Carbonado is an extensible, high performance persistence abstraction layer for Java applications, providing a relational view to the underlying persistence technology. Persistence can be provided by a JDBC accessible SQL relational database, or it can be a BDB. It can also be fully replicated between the two.
Even if the backing database is not SQL based, Carbonado still supports many of the core features found in any kind of relational database. It supports queries, joins, indexes, and it performs query optimization. When used in this way, Carbonado is not merely a layer to a relational database, it is the relational database. SQL is not a requirement for implementing relational databases.
The Amazon engineers who collaborated on developing Carbonado over time received feedback that there was a lot of interest in the developer community outside of Amazon for this technology. We decided to release this software through an open source process for other developers to use, improve and extend.
Congratulation to Brian and his close collaborators for developing excellent technology and putting in the work to make it publicly available and to Don, Ryan and Stephanie for navigating all the legal and other obstacles to make this a reality.