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From arun sirimalla <arunsi...@gmail.com>
Subject Re: Read Consistency
Date Tue, 23 Jun 2015 18:26:28 GMT
So do you mean with CL set to QUORUM, if data is only on one node, the
query still succeeds.

On Tue, Jun 23, 2015 at 11:21 AM, Philip Thompson <
philip.thompson@datastax.com> wrote:

> Anuj,
>
> In the first scenario, the data from the single node holding data is
> returned. The query will not fail if the consistency level is met, even if
> the read was inconsistent.
>
> On Tue, Jun 23, 2015 at 2:16 PM, Anuj Wadehra <anujw_2003@yahoo.co.in>
> wrote:
>
>> Why would it fail and with what Thrift error? What if the data didnt
>> exist on any of the nodes..query wont fail if doesnt find data..
>>
>> Not convinced..
>>
>> Sent from Yahoo Mail on Android
>> <https://overview.mail.yahoo.com/mobile/?.src=Android>
>> ------------------------------
>>   *From*:"arun sirimalla" <arunsirik@gmail.com>
>> *Date*:Tue, 23 Jun, 2015 at 11:39 pm
>> *Subject*:Re: Read Consistency
>>
>> Scenario 1: Read query is fired for a key, data is found on one node and
>> not found on other two nodes who are responsible for the token
>> corresponding to key.
>>
>> You read query will fail, as it expects to receive data from 2 nodes with
>> RF=3
>>
>>
>> Scenario 2: Read query is fired and all 3 replicas have different data
>> with different timestamps.
>>
>> Read query will return the data with most recent timestamp and trigger a
>> read repair in the backend .
>>
>> On Tue, Jun 23, 2015 at 10:57 AM, Anuj Wadehra <anujw_2003@yahoo.co.in>
>> wrote:
>>
>>> Hi,
>>>
>>> Need to validate my understanding..
>>>
>>> RF=3 , Read CL = Quorum
>>>
>>> What would be returned to the client in following scenarios:
>>>
>>> Scenario 1: Read query is fired for a key, data is found on one node and
>>> not found on other two nodes who are responsible for the token
>>> corresponding to key.
>>>
>>> Options: no data is returned OR data from the only node having data is
>>> returned?
>>>
>>> Scenario 2: Read query is fired and all 3 replicas have different data
>>> with different timestamps.
>>>
>>> Options: data with latest timestamp is returned OR something else???
>>>
>>> Thanks
>>> Anuj
>>>
>>> Sent from Yahoo Mail on Android
>>> <https://overview.mail.yahoo.com/mobile/?.src=Android>
>>>
>>
>>
>>
>> --
>> Arun
>>
>
>


-- 
Arun
Senior Hadoop/Cassandra Engineer
Cloudwick


2014 Data Impact Award Winner (Cloudera)
http://www.cloudera.com/content/cloudera/en/campaign/data-impact-awards.html

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