[jira] Commented: (CASSANDRA-132) Support (limited) session level consistency

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12711755#action_12711755 ] 

Jonathan Ellis commented on CASSANDRA-132:
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I'm not sure about this part

                // Check if local. Don't need to check if this is a hinted
                // message because we don't send hints from local to local

We won't send a message hinted for A to node A, but we could send a message to A hinted for B, if B is down.   No?

> Support (limited) session level consistency
> -------------------------------------------
>
>                 Key: CASSANDRA-132
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-132
>             Project: Cassandra
>          Issue Type: Improvement
>    Affects Versions: trunk
>         Environment: all
>            Reporter: Sandeep Tata
>            Assignee: Sandeep Tata
>             Fix For: trunk
>
>         Attachments: CASSANDRA-132.patch
>
>
> Limited session-level consistency: if the client connects to a node and performs operations on rows/keys that are local to that node (in that node's key range), we should be able to guarantee read-your-writes consistency. If the session ends because of a failure, and the client has to reconnect, there are no guarantees across the sessions.
> (This is a common practical variation of eventual consistency, see: http://www.allthingsdistributed.com/2008/12/eventually_consistent.html for context.)
> Supporting this for a "local" sessions is significantly easier than supporting session level consistency when the node does not own the data. A non-owning node that is reading values from a remote replica will need to either do 
> a) quorum reads and writes to guarantee session level read-your-writes
> b) pick at least one node to block on and stick to that node as a "master" for the session.

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