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From Shahab Yunus <shahab.yu...@gmail.com>
Subject Re: what happen if coordinator node fails during write
Date Sat, 29 Jun 2013 15:11:03 GMT
Aaron,

Can you explain a bit when you say that the client needs to support Atomic
Batches in 1.2 and Hector doesn't support it? Does it mean that there is no
way of using atomic batch of inserts through Hector? Or did I misunderstand
you? Feel free to point me to any link or resource, thanks.

Regards,
Shahab

On Friday, June 28, 2013, aaron morton wrote:

> As far as I know in 1.2 coordinator logs request before it updates
> replicas.
>
> You may be thinking about atomic batches, which are enabled by default for
> 1.2 via CQL but must be supported by Thrift clients. I would guess Hector
> is not using them.
> These logs are stored on other machines, which then reply the mutation if
> they have not been removed by a certain time.
>
>
>> I am writing data to Cassandra by thrift client (not hector) and
>> wonder what happen if the coordinator node fails.
>
> How and when it fails is important.
> But lets say their was an OS level OOM situation and the process was
> killed just after it sent messages to the remote replicas. In that case all
> you know if the request was applied on 0 to RF number of replicas. So it's
> the same as a TimedOutException.
>
> The request did not complete at the request CL so reads to that data will
> be working eventual consistency until the next successful write.
>
> Cheers
>
>
> -----------------
> Aaron Morton
> Freelance Cassandra Consultant
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 26/06/2013, at 12:45 PM, Andrey Ilinykh <ailinykh@gmail.com<javascript:_e({},
'cvml', 'ailinykh@gmail.com');>>
> wrote:
>
> It depends on cassandra version. As far as I know in 1.2 coordinator logs
> request before it updates replicas. If it fails it will replay log on
> startup.
> In 1.1 you may have inconsistant state, because only part of your request
> is propagated to replicas.
>
> Thank you,
>   Andrey
>
>
> On Tue, Jun 25, 2013 at 5:11 PM, Jiaan Zeng <jiaan@bloomreach.com<javascript:_e({},
'cvml', 'jiaan@bloomreach.com');>
> > wrote:
>
>> Hi there,
>>
>> I am writing data to Cassandra by thrift client (not hector) and
>> wonder what happen if the coordinator node fails. The same question
>> applies for bulk loader which uses gossip protocol instead of thrift
>> protocol. In my understanding, the HintedHandoff only takes care of
>> the replica node fails.
>>
>> Thanks.
>>
>> --
>> Regards,
>> Jiaan
>>
>
>
>

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