cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Sam Overton (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4123) vnodes aware Replication Strategy
Date Mon, 09 Jul 2012 17:18:35 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4123?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13409655#comment-13409655
] 

Sam Overton commented on CASSANDRA-4123:
----------------------------------------

{noformat}
        Set<InetAddress> replicas = new HashSet<InetAddress>();
        // replicas we have found in each DC
        Map<String, Set<InetAddress>> dcReplicas = new HashMap<String, Set<InetAddress>>(datacenters.size())
{noformat}

They're both sets, and we're using the .size() of the set to establish whether we have found
sufficient replicas, so whilst we do add the same endpoint twice, it is effectively a no-op.
                
> vnodes aware Replication Strategy 
> ----------------------------------
>
>                 Key: CASSANDRA-4123
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4123
>             Project: Cassandra
>          Issue Type: Sub-task
>          Components: Core
>            Reporter: Sam Overton
>            Assignee: Sam Overton
>
> The simplest implementation for this would be if NTS regarded a single host as a distinct
rack. This would prevent replicas being placed on the same host. The rest of the logic for
replica selection would be identical to NTS (but this would be removing a level of topology
hierarchy). This would be achievable just by writing a snitch to place hosts in their own
rack.
> A better solution would be to add an extra level of hierarchy to NTS so that it still
supported DC & rack, and IP would be the new level at the bottom of the hierarchy. The
logic would remain largely the same.
> I would very much like to build in Peter Schuller's notion of Distribution Factor (as
described in http://www.mail-archive.com/dev@cassandra.apache.org/msg03844.html). This requires
a method of defining a "replica set" for each host and then treating it in a similar way to
a DC (ie. RF replicas are chosen from that set, instead of from the whole cluster). 

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message