- one of the Base Availability Soft_state Eventually_consistent storage
- using CassandraQueryLanguage for querying data
- no master, managed by background daemon process
- KeySpace
- ColumnFamily
- Column
- Key
FamilyColumn <>---------- Column
SuperFamilyColumn <>----- SuperColumn CompositeColumn
- one: from first node
- quorum: when more than 50% of nodes responded
- all ( consistent ): when all nodes answered
- zero: no wait, just send data and close connection by client
- any: at least one node should answered
- one: node answered, commit log was written, new value placed in memory
- quorum: more than 50% confirmed
- all: all nodes confirmed writing