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The "DataModel" page has been changed by PatriciaGorla: http://wiki.apache.org/cassandra/DataModel?action=diff&rev1=30&rev2=31 } } }}} - Note that the key "mccv" identifies data in two different column families, "Users" and "Stats". This does not imply that data from these column families is related. The semantics of having data for the same key in two different column families is entirely up to the application. Also note that within the "Users" column family, "mccv" and "user2" have different column names defined. This is perfectly valid in Cassandra. In fact there may be a virtually unlimited set of column names defined, which leads to fairly common use of the column name as a piece of runtime populated data. This is unusual in storage systems, particularly if you're coming from the RDBMS world. + Note that the key "row_key1" identifies data in two different column families, "Users" and "Stats". This does not imply that data from these column families is related. The semantics of having data for the same key in two different column families is entirely up to the application. Also note that within the "Users" column family, "row_key1" and "row_key2" have different column names defined. This is perfectly valid in Cassandra. In fact there may be a virtually unlimited set of column names defined, which leads to fairly common use of the column name as a piece of runtime populated data. This is unusual in storage systems, particularly if you're coming from the RDBMS world. = Keyspaces = A keyspace is the first dimension of the Cassandra hash, and is the container for column families. Keyspaces are of roughly the same granularity as a schema or database (i.e. a logical collection of tables) in the RDBMS world. They are the configuration and management point for column families, and is also the structure on which batch inserts are applied.
