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From Gary Dusbabek <>
Subject Re: Locking in cassandra
Date Mon, 16 Aug 2010 13:13:19 GMT
>From a cluster perspective there is no locking, atomicity or
isolation.  In your example, 5 nodes may be written to and if a 6th
write doesn't happen, the write is failed, but the 5 writes that
happened stay.

The code is in two places.  StorageProxy.mutate (and mutateBlocking)
is where the local write happens (if a coordinator is reponsible for
the mutation key).  RowMutationVerbHandler does the same work on the
remote nodes and acknowledges the writes.


On Mon, Aug 16, 2010 at 08:07, Maifi Khan <> wrote:
> Hi
> How is the locking implemented in cassandra? Say, I have 10 nodes and
> I want to write to 6 nodes which is (n+1)/2.
> Will it lock 6 nodes first and then start writing? Or will it write
> one by one and see if it can write to 6 nodes.
> How is this implemented? What package does this locking?
> Thanks in advance.
> thanks

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