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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Atomic Operations in Cassandra
Date Sun, 11 Dec 2011 16:14:02 GMT
On Sun, Dec 11, 2011 at 12:01 PM, Boris Yen <yulinyen@gmail.com> wrote:
> Hi Sylvain,
>
> "Writes under the same row key are atomic (even across column families) in
> the
> sense that they are either all persisted or none are."
>
> Is this new feature for 1.x, or it also applies to previous version of
> Cassandra?

It applies to previous version of Cassandra.

--
Sylvain

>
> Boris
>
>
> On Thu, Dec 8, 2011 at 6:40 PM, Sylvain Lebresne <sylvain@datastax.com>
> wrote:
>>
>> On Thu, Dec 8, 2011 at 12:57 AM, Christof Bornhoevd
>> <cbornhoevd@gmail.com> wrote:
>> > Hi All,
>> >
>> > I'm using Cassandra 1.0.3 (with Hector 0.7). What is the granularity of
>> > atomic read and write operations with Cassandra. I.e. is the insert or
>> > update of an individual column an atomic operation (in the sense that it
>> > either fails or persists completely), or is the insert or update of an
>> > entire row in a ColumnFamily atomic?
>> >
>> > Similarly, if I read multiple columns of the same row, could the read
>> > operation interfere with a concurrent write operation on these same
>> > columns
>> > in a way that I might see some old and some new column values?
>>
>> Writes under the same row key are atomic (even across column families) in
>> the
>> sense that they are either all persisted or none are. Note however that it
>> is
>> possible for a insertion to fail for the client (say you get a
>> TimeoutException) but
>> for the insertion to still be persisted.
>> There is however no isolation currently. It is possible for a read to
>> see a state
>> where only part of an insertion (even within the same row key) has been
>> applied.
>> (CASSANDRA-2893 is open to try to add isolation).
>>
>> --
>> Sylvain
>>
>> >
>> > Cheers and thanks a lot for any kind help on this!
>> > Chris
>
>

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