Apache Cassandra mixes features of key-value and traditional relational databases. In a conventional relational database, the columns of a table are fixed. In Cassandra, however, rows within the same table can have different columns. Cassandra is therefore column oriented, since it allows a flexible schema for each row. Columns are organized in so-called column families, which are equivalent to tables in relational databases. Joins and subqueries are not possible with Cassandra. Cassandra can be downloaded from http://cassandra.apache.org/download/. The latest version at the time of writing was 2.0.9. Please refer to http://wiki.apache.org/cassandra/GettingStarted to get started.

Run the server from the command line as follows:

$ bin/cassandra –f

If you run the previous command, you may get the following error message:

Cassandra 2.0 and later require Java 7 or later.

Java in this context is a high-level programming language such as Python. Java 7 refers to version 1.7...