Cassandra is an open source distributed database, it combines dynamic key/value and column oriented feature of Bigtable.Features of Cassandra are:Flexible schema, no need to design schema first, it's very convenient to add or delete stringsSupport range search on keysHigh usability, extensible. The single node error will not affect the cluster.We can think Cassandra's data model as a 4 or 5 dimensional Hash.COLUMNColumns is the smallest data unit in Cassandra, it is a 3 dimensional data type including name,value and timestamp. { // This is a column name: "逖靖寒的�...