Package cassandra: Information

Cassandra brings together the distributed systems technologies from Dynamo
and the data model from Google's BigTable. Like Dynamo, Cassandra is
eventually consistent. Like BigTable, Cassandra provides a ColumnFamily-based
data model richer than typical key/value systems.

Compared to other databases, three big features stand out:

 * Flexible schema: with Cassandra, like a document store, you don't have
   to decide what fields you need in your records ahead of time.
   You can add and remove arbitrary fields on the fly.
   This is an incredible productivity boost, especially in large deployments.

 * True scalability: Cassandra scales horizontally in the purest sense.
   To add more capacity to a cluster, turn on another machine.
   You don't have restart any processes, change your application queries,
   or manually relocate any data.

 * Multi-datacenter awareness: you can adjust your node layout to ensure that
   if one datacenter burns in a fire, an alternative datacenter will have at
   least one full copy of every record.

Some other features that help put Cassandra above the competition:

 * Range queries: unlike most key/value stores, you can query for ordered
   ranges of keys.

 * List datastructures: super columns add a 5th dimension to the hybrid model,
   turning columns into lists. This is very handy for things like per-user
   indexes.

 * Distributed writes: you can read and write any data to anywhere in the
   cluster at any time. There is never any single point of failure.

For more information see http://incubator.apache.org/cassandra

Package cassandra: Information

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