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https://issues.apache.org/jira/browse/CASSANDRA-197?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12712176#action_12712176
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Jun Rao commented on CASSANDRA-197:
-----------------------------------
If you look at the original Dynamo paper, it definitely talks about exposing
key locations for shorter network path.
You can think of RingCache part of the cassandra client library. It's just a
cache and only serves as hints. Note that bigtable/Hbase expose the locality to
clients too. Ideally, such exposure should be hidden in the client library.
However, this is a bit hard to do in Cassandra since the client code is
generated by Thrift. In any case, I don't see any harm for exposing such
information.
As for the endpoint_for_key call, this will force the client to cache the
location for every row, which is likely more expensive.
> Expose ring map to client for more direct access
> ------------------------------------------------
>
> Key: CASSANDRA-197
> URL: https://issues.apache.org/jira/browse/CASSANDRA-197
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Jun Rao
> Assignee: Jun Rao
> Attachments: issue197.patchv1
>
>
> For certain applications, it would be nice if a read is sent to a node that
> owns the data locally. This saves an extra network hop. To do that, a client
> will need to cache the ring map and use it to figure out the nodes owning a
> row.
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