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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "FAQ" by RobertColi
Date Mon, 27 Sep 2010 16:39:08 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Cassandra Wiki" for change notification.

The "FAQ" page has been changed by RobertColi.
The comment on this change is: clarification on batch_mutate_atomic using info from jbellis@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)>>
  

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