Coming up in Cassandra 1.1: Row Level Isolation | DataStax
While Apache Cassandra does not provide ACID properties (no complex transactions support), it still provides some useful atomicity guarantees.
More precisely, Cassandra has always provided row-level atomicity of batch mutations. This means that multiple batched writes to the same row are applied by nodes atomically. When doing
UPDATE Users
SET login='eric22' AND password='f3g$dq!'
WHERE key='550e8400-e29b-41d4-a716-446655440000'
Cassandra guarantees that the changes to login and password are either both applied or none are.
However, up to Cassandra 1.0, the isolation of such an update was not guaranteed. In other words, it is possible (during a very brief moment during the update) that a read like
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