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https://issues.apache.org/jira/browse/CASSANDRA-9602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14942242#comment-14942242
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Gary Stewart commented on CASSANDRA-9602:
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In (certain) versions 2.0 this was supported:
http://docs.datastax.com/en/cassandra/2.0/cassandra/dml/dml_config_consistency_c.html
In version 2.1 it is now suddenly not supported.
http://docs.datastax.com/en/cassandra/2.1/cassandra/dml/dml_config_consistency_c.html
This is actually a breaking change in the upgrade path and will hurt clients
especially when using it for multi-tenancy solutions.
Our use-case is is very heavy writes where latency matters thus we choose
CL=LOCAL_QUORUM and seriously few reads where latency does not matter thus we
choose to use CL=EACH_QUORUM. This is the minimum to ensure strong consistency
which we also need. Now, we are now forced to change to ALL with downgrading
consistency.
> 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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