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https://issues.apache.org/jira/browse/CASSANDRA-1530?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Joaquin Casares updated CASSANDRA-1530:
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Attachment: 1530-joaquin.txt
I added some code to RowMutationVerbHandler to check for forward hints, the
forward hint variable to RowMutation, and quite a few lines to StorageProxy
including an additional function addForwardHintHeader to facilitate the
creation of forward hints.
I've left the comments for which sections I coded to serve as a clear indicator
when the code is merged.
// TODO avoid creating map until we find a target that's not in the same
datacenter as the current node
// TODO refactor out addhint/addforwardhint method
// TODO simplify import org.apache.cassandra.locator.*; in StorageProxy.
> More-efficient cross-DC replication
> -----------------------------------
>
> Key: CASSANDRA-1530
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1530
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Fix For: 0.7.1
>
> Attachments: 1530-joaquin.txt
>
>
> Currently the coordinator node sends writes to each replica. In multi-dc
> situations, it would be more efficient to have the coordinator talk to a
> single node in each DC, which would forward the writes to the other replicas
> local to it. (All replicas would continue to ack to the coordinator.)
> Shouldn't be difficult to add a header to RMVH saying "consult the Strategy
> to see who else is local to you and queue it off to them as well."
> For example, consider two data centers with the following nodes:
> DC1: A, B, C
> DC2: D, E, F
> A client connected to node A performs an insert that should be replicated to
> {B,C,E,F}. Currently, A will send a MUTATION verb to each of those nodes
> directly. But communication to E and F is relatively expensive since they
> are in the other data center from A. So we'd like to send the mutation to
> just one, say E, with a tag saying "forward this to F as well."
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