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From Ajay Garg <ajaygargn...@gmail.com>
Subject Re: Doubt regarding consistency-level in Cassandra-2.1.10
Date Wed, 04 Nov 2015 03:21:22 GMT
Hmm... ok.

Ideally, we require ::

a)
The intra-DC-node-syncing takes place at the statement/query level.

b)
The inter-DC-node-syncing takes place at cassandra level.


That way, we don't spend too much delay at the statement/query level.


For the so-called CAS/lightweight transactions, the above are impossible
then?

On Wed, Nov 4, 2015 at 5:58 AM, Bryan Cheng <bryan@blockcypher.com> wrote:

> What Eric means is that SERIAL consistency is a special type of
> consistency that is only invoked for a subset of operations: those that use
> CAS/lightweight transactions, for example "IF NOT EXISTS" queries.
>
> The differences between CAS operations and standard operations are
> significant and there are large repercussions for tunable consistency. The
> amount of time such an operation takes is greatly increased as well; you
> may need to increase your internal node-to-node timeouts .
>
> On Mon, Nov 2, 2015 at 8:01 PM, Ajay Garg <ajaygargnsit@gmail.com> wrote:
>
>> Hi Eric,
>>
>> I am sorry, but I don't understand.
>>
>> If there had been some issue in the configuration, then the
>> consistency-issue would be seen everytime (I guess).
>> As of now, the error is seen sometimes (probably 30% of times).
>>
>> On Mon, Nov 2, 2015 at 10:24 PM, Eric Stevens <mightye@gmail.com> wrote:
>>
>>> Serial consistency gets invoked at the protocol level when doing
>>> lightweight transactions such as CAS operations.  If you're expecting that
>>> your topology is RF=2, N=2, it seems like some keyspace has RF=3, and so
>>> there aren't enough nodes available to satisfy serial consistency.
>>>
>>> See
>>> http://docs.datastax.com/en/cassandra/2.0/cassandra/dml/dml_ltwt_transaction_c.html
>>>
>>> On Mon, Nov 2, 2015 at 1:29 AM Ajay Garg <ajaygargnsit@gmail.com> wrote:
>>>
>>>> Hi All.
>>>>
>>>> I have a 2*2 Network-Topology Replication setup, and I run my
>>>> application via DataStax-driver.
>>>>
>>>> I frequently get the errors of type ::
>>>> *Cassandra timeout during write query at consistency SERIAL (3 replica
>>>> were required but only 0 acknowledged the write)*
>>>>
>>>> I have already tried passing a "write-options with LOCAL_QUORUM
>>>> consistency-level" in all create/save statements, but I still get this
>>>> error.
>>>>
>>>> Does something else need to be changed in /etc/cassandra/cassandra.yaml
>>>> too?
>>>> Or may be some another place?
>>>>
>>>>
>>>> --
>>>> Regards,
>>>> Ajay
>>>>
>>>
>>
>>
>> --
>> Regards,
>> Ajay
>>
>
>


-- 
Regards,
Ajay

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