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Date: Wed, 24 Mar 2010 06:03:27 +0000 (UTC)
From: "Stu Hood (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Subject: [jira] Commented: (CASSANDRA-749) Secondary indices for column
 families
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    [ https://issues.apache.org/jira/browse/CASSANDRA-749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12849069#action_12849069 ] 

Stu Hood commented on CASSANDRA-749:
------------------------------------

Cliff mentioned in #cassandra that he preferred the local secondary index approach. I think this was because adding more replicas is supposed to be a solution for scaling out reads, but I don't think it is that simple here.

Rather than utilizing IO efficiently by partitioning, all of those nodes will have approximately the same stuff cached in memory, because they won't have been assigned anything specific to hold onto. Also, scaling up to more replicas (than you need for HA) across your entire cluster in order to improve your average latency seems like a waste of disks/machines.

Additionally, you have to keep all of those replicas consistent, which means every node still has to answer reads eventually for read repair. Adding nodes doesn't actually eliminate any queries: it might improve your average latency, but it won't affect your throughput.

> Secondary indices for column families
> -------------------------------------
>
>                 Key: CASSANDRA-749
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-749
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Gary Dusbabek
>            Assignee: Gary Dusbabek
>            Priority: Minor
>             Fix For: 0.8
>
>         Attachments: 0001-simple-secondary-indices.patch, views-discussion-2.txt, views-discussion.txt
>
>


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