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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6477) Global indexes
Date Thu, 05 Mar 2015 04:33:42 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14348113#comment-14348113
] 

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

bq. This is going to be very similar to CASSANDRA-8234

Similar conceptually, but much simpler in practice since 8234 envisions arbitrary joins and
subqueries that you need something like hadoop or spark for.  Here we're just scanning a single
table.  Easy enough to send a message out to the cluster to emit inserts on the 2i table for
their local data.  (And yes, we're fine with taking the hit of doing this inefficiently for
now.  To optimize you could pick just one replica to do the repaired parts, and then everyone
does the unrepaired.)

bq. Denormalizing all the columns (DENORMALIZED (*))

IMO this should be the default, and {{WITH DENORMALIZED (...)}} syntax could optionally restrict
it.

> 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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