Scott Guminy created CASSANDRA-9602:
---------------------------------------
Summary: EACH_QUORUM READ support needed
Key: CASSANDRA-9602
URL: https://issues.apache.org/jira/browse/CASSANDRA-9602
Project: Cassandra
Issue Type: Bug
Reporter: Scott Guminy
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 in this defect is 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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
