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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: Read Consistency
Date Tue, 23 Jun 2015 18:23:54 GMT
Btw, Hope you'll find the answers you could not ask in today online lesson
;-).

C*heers

2015-06-23 20:22 GMT+02:00 Alain RODRIGUEZ <arodrime@gmail.com>:

> Hi,
>
> I do not agree with Scenario 1 result Arun,
>
> The 2 nodes don't have the data yet are available. IMHO what happens next
> i a slow read since it will have to perform read repair and coordinator
> will send back the result and an 'OK' message.Consistency is not met when
> nor enough nodes were up.
>
> Agreed on scenario 2. I would add that one repair will be synchronous and
> mandatory while the second depends on your read repair chance parameter on
> this table and is async.
>
> C*heers
>
> 2015-06-23 20:16 GMT+02:00 Anuj Wadehra <anujw_2003@yahoo.co.in>:
>
>> 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
>>
>
>

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