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

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

    [ https://issues.apache.org/jira/browse/CASSANDRA-1530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12991519#comment-12991519 ] 

Jonathan Ellis edited comment on CASSANDRA-1530 at 2/7/11 7:15 PM:
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v2 fixes use of messageId you caught.

I didn't get rid of LB because I'm cleaning up VerbHandlers here (since they're the primary users of messageId) so I thought I could stretch my mandate that far. :)

v2 includes regeneration of .bin files -- it looks like svn diff is picking up some but not all of them.  SerializationsTest is passing so I assume it will be fine on commit.

      was (Author: jbellis):
    v2 fixes use of messageId you caught.

I didn't get rid of LB because I'm cleaning up VerbHandlers here (since they're the primary users of messageId) so I thought I could stretch my mandate that far. :)

v2 includes regeneration of .bin files -- it looks like svn diff is picking up some but all of them.  SerializationsTest is passing so I assume it will be fine on commit.
  
> 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
>            Assignee: Jonathan Ellis
>             Fix For: 0.7.1
>
>         Attachments: 1530-2-v2.txt, 1530-2.txt
>
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> 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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