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The "FAQ" page has been changed by RobertColi. The comment on this change is: clarification on batch_mutate_atomic using info from jbel...@cassandra-user :). http://wiki.apache.org/cassandra/FAQ?action=diff&rev1=84&rev2=85 -------------------------------------------------- <<Anchor(batch_mutate_atomic)>> == Are batch_mutate operations atomic? == - As a special case, mutations against a single key are atomic, but more generally no. [[API#batch_mutate|batch_mutate]] allows grouping operations on many keys into a single call in order to save on the cost of network round-trips. If `batch_mutate` fails in the middle of its list of mutations, no rollback occurs and the mutations that have already been applied stay applied. The client should typically retry the `batch_mutate` operation. + As a special case, mutations against a single key are atomic but not isolated. Reads which occur during such a mutation may see part of the write before they see the whole thing. More generally, batch_mutate operations are not atomic. [[API#batch_mutate|batch_mutate]] allows grouping operations on many keys into a single call in order to save on the cost of network round-trips. If `batch_mutate` fails in the middle of its list of mutations, no rollback occurs and the mutations that have already been applied stay applied. The client should typically retry the `batch_mutate` operation. <<Anchor(hadoop_support)>>
