Re: what happen if coordinator node fails during write
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
ailin...@gmail.comjavascript:_e({}, 'cvml', 'ailin...@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
ji...@bloomreach.comjavascript:_e({}, 'cvml', 'ji...@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
Re: what happen if coordinator node fails during write
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 ailin...@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 ji...@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
Re: what happen if coordinator node fails during write
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 ji...@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
Re: what happen if coordinator node fails during write
Read this http://www.datastax.com/dev/blog/atomic-batches-in-cassandra-1-2 On Tue, Jun 25, 2013 at 8:45 PM, Andrey Ilinykh ailin...@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 ji...@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
