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https://issues.apache.org/jira/browse/CASSANDRA-9602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14943818#comment-14943818
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Daniel Cohen commented on CASSANDRA-9602:
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[~oseiler]: [~stewartg] and I agree that we all want EACH_QUORUM reads.
I also agree that this was in fact never supported in Cassandra, and at the
very least the C* v2.0 documentation was a little confusing. Check out this
link to the OSS C* code:
https://git1-us-west.apache.org/repos/asf?p=cassandra.git;a=commitdiff;h=72199e23ec9d604449bef87733a32e1da9924437
In particular there is a comment regarding a change as of C* v1.1:
{quote}EACH_QUORUM ConsistencyLevel is only supported for writes and will now
+ throw an InvalidRequestException when used for reads. (Previous
+ versions would silently perform a LOCAL_QUORUM read instead.){quote}
> EACH_QUORUM READ support needed
> -------------------------------
>
> Key: CASSANDRA-9602
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9602
> Project: Cassandra
> Issue Type: Sub-task
> Reporter: Scott Guminy
> Assignee: Carl Yeksigian
> Labels: client-impacting, doc-impacting
> Fix For: 3.x
>
>
> EACH_QUORUM consistency for READ should be added.
> This bug https://issues.apache.org/jira/browse/CASSANDRA-3272 says it is not
> needed ever, however I have a use case where I need it. I think the decision
> made was incorrect. Here's why...
>
> My application has two key pieces:
>
> # *End user actions* which add/modify data in the system. End users
> typically access the application from only one Data Center and only see their
> own data
> # *Scheduled business logic tasks* which run from any node in any data
> center. These tasks process data added by the end users in an asynchronous
> way
>
> *End user actions must have the highest degree of availability.* Users must
> always be able to add data to the system. The data will be processed later.
> To support this, end user actions will use *LOCAL_QUORUM Read and Write
> Consistency*.
>
> Scheduled tasks don't need to have a high degree of availability but MUST
> operate on the most up to date data. *The tasks will run with EACH_QUORUM*
> to ensure that no matter how many data centers we have, we always READ the
> latest data. This approach allows us some amount of fault tolerance.
>
> The problem is that EACH_QUORUM is not a valid READ consistency level. This
> mean I have no alternative but to use ALL. ALL will work, but is not the
> best since it offers support for ZERO failures. I would prefer EACH_QUORUM
> since it can support some failures in each data center.
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