Apache Cassandra

Cassandra was open sourced by Facebook in 2008, and is now developed by Apache committers and contributors from many companies.

SOME DEFINITIONS:

Stable releases

Cassandra stable releases are well tested and reasonably free of serious problems, (or at least the problems are known and well documented). If you are setting up a production environment, a stable release is what you want.

Betas and release candidates

Betas are prototype releases considered ready for user testing, and release candidates have the potential to become the next stable release. These releases represent the state-of-the-art so are often the best place to start, and since APIs and on-disk storage formats can change between major versions this can also save you from an upgrade. The testing and feedback is also highly appreciated.

Nightly builds

Nightly builds represent the current state of development as of the time of the build. They contain all of the previous day's new features, fixes, and newly introduced bugs. The only guarantee they come with is that they successfully build and the unit tests pass. Nightly builds are a handy way of testing recent changes, or accessing the latest features and fixes not found in beta or release candidates, but there is some risk of them being buggy.