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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6477) Global indexes
Date Wed, 15 Apr 2015 22:52:02 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14497174#comment-14497174
] 

Jonathan Ellis commented on CASSANDRA-6477:
-------------------------------------------

bq. we would need to have a single replica that we push all index updates through

You're right, that doesn't work.

bq. it would very difficult to determine whether a grouping of updates indicates simultaneous
updates or just a series of updates that happened to use the same values

I don't think that makes it not work.  Each of those values is a separate partition.  I think
we get the right answer if we just take the highest value for each partition and delete any
"ghost" entries that may have been missed.

> Global indexes
> --------------
>
>                 Key: CASSANDRA-6477
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6477
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>            Assignee: Carl Yeksigian
>              Labels: cql
>             Fix For: 3.0
>
>
> Local indexes are suitable for low-cardinality data, where spreading the index across
the cluster is a Good Thing.  However, for high-cardinality data, local indexes require querying
most nodes in the cluster even if only a handful of rows is returned.



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