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Posted to commits@cassandra.apache.org by "Jonathan Ellis (JIRA)" <ji...@apache.org> on 2010/10/15 18:18:37 UTC

[jira] Issue Comment Edited: (CASSANDRA-1530) More-efficient cross-DC replication

    [ https://issues.apache.org/jira/browse/CASSANDRA-1530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12921215#action_12921215 ] 

Jonathan Ellis edited comment on CASSANDRA-1530 at 10/15/10 12:17 PM:
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The coordinator node creates messages in StorageProxy.  There are two approaches you could take: annotate the Header the way we do for hints, or create a different verb for write-and-forward.

      was (Author: jbellis):
    The coordinator node creates messages in StorageProxy.  There are two approaches you could take: annotate the Header the way we do for hints, and create a different verb for write-and-forward.
  
> 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
>
>
> 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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