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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6477) Materialized Views (was: Global Indexes)
Date Tue, 14 Jul 2015 14:35:09 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14626399#comment-14626399
] 

T Jake Luciani commented on CASSANDRA-6477:
-------------------------------------------

bq.  Creating a MV where the partition key is for instance the gender of your users is equally
going to create massive hotspots, but it's not like we can forbid people to do it.

This is an obvious anti-pattern for a materialized view.  NULL, however, is not something
people think about since it's the default value implicitly for Cassandra.  Especially when
considering consistency issues in a dynamo system.  If you are writing to a table with RF=3
and only one replica has a value but the other two do not then we will make one MV replica
have a defined partition key and the other two replicas will have a NULL. Currently we don't
allow this so the NULLs are left out.  


> Materialized Views (was: 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 beta 1
>
>         Attachments: test-view-data.sh, users.yaml
>
>
> 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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