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Posted to user@cassandra.apache.org by Chris Burroughs <ch...@gmail.com> on 2014/02/06 14:31:29 UTC
Re: Question: ConsistencyLevel.ONE with multiple datacenters
I think the scenario you outlined is correct. The DES handles multiple
DCs poorly and the LOCAL_ONE hammer is the best bet.
On 01/31/2014 12:40 PM, Paulo Ricardo Motta Gomes wrote:
> Hey,
>
> When adding a new data center to our production C* datacenter using the
> procedure described in [1], some of our application requests were returning
> null/empty values. Rebuild was not complete in the new datacenter, so my
> guess is that some requests were being directed to the brand new datacenter
> which still didn't have the data.
>
> Our Hector client was connected only to the original nodes, with
> autoDiscoverHosts=false and we use ConsistencyLevel.ONE for reads. The
> keyspace schema was already configured to use both data centers.
>
> My question is: is it possible that the dynamic snitch is choosing the
> nodes in the new (empty) datacenter when CL=ONE? In this case, it's
> mandatory to use CL=LOCAL_ONE during bootstrap/rebuild of a new datacenter,
> otherwise empty data might be returned, correct?
>
> Cheers,
>
> [1]
> http://www.datastax.com/documentation/cassandra/1.2/webhelp/cassandra/operations/ops_add_dc_to_cluster_t.html
>
Re: Question: ConsistencyLevel.ONE with multiple datacenters
Posted by Paulo Ricardo Motta Gomes <pa...@chaordicsystems.com>.
Cool. I actually changed the consistency level to LOCAL_ONE and things
worked as expected.
Cheers!
On Thu, Feb 6, 2014 at 11:31 AM, Chris Burroughs
<ch...@gmail.com>wrote:
> I think the scenario you outlined is correct. The DES handles multiple
> DCs poorly and the LOCAL_ONE hammer is the best bet.
>
>
> On 01/31/2014 12:40 PM, Paulo Ricardo Motta Gomes wrote:
>
>> Hey,
>>
>> When adding a new data center to our production C* datacenter using the
>> procedure described in [1], some of our application requests were
>> returning
>> null/empty values. Rebuild was not complete in the new datacenter, so my
>> guess is that some requests were being directed to the brand new
>> datacenter
>> which still didn't have the data.
>>
>> Our Hector client was connected only to the original nodes, with
>> autoDiscoverHosts=false and we use ConsistencyLevel.ONE for reads. The
>> keyspace schema was already configured to use both data centers.
>>
>> My question is: is it possible that the dynamic snitch is choosing the
>> nodes in the new (empty) datacenter when CL=ONE? In this case, it's
>> mandatory to use CL=LOCAL_ONE during bootstrap/rebuild of a new
>> datacenter,
>> otherwise empty data might be returned, correct?
>>
>> Cheers,
>>
>> [1]
>> http://www.datastax.com/documentation/cassandra/1.2/
>> webhelp/cassandra/operations/ops_add_dc_to_cluster_t.html
>>
>>
>
--
*Paulo Motta*
Chaordic | *Platform*
*www.chaordic.com.br <http://www.chaordic.com.br/>*
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