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Posted to commits@cassandra.apache.org by "Tony Zhao (JIRA)" <ji...@apache.org> on 2013/06/20 22:40:20 UTC

[jira] [Created] (CASSANDRA-5679) Wide Row calls map method once per column in Hadoop MapReduce

Tony Zhao created CASSANDRA-5679:
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             Summary: Wide Row calls map method once per column in Hadoop MapReduce
                 Key: CASSANDRA-5679
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5679
             Project: Cassandra
          Issue Type: Bug
          Components: Hadoop
    Affects Versions: 1.2.4
         Environment: CentOS 6.3, Hadoop 1.1.2, Cassandra 1.2.4
            Reporter: Tony Zhao


When using Cassandra without wide row support in a Hadoop job, the map method gets a number of columns limited by the SlicePredicate every time the map method in the mapper is called; but when using wide row support, the map method is called once for every column. It seems like the limit in SlicePredicate is ignored when wide row set to true. 

This prevents in-map reducing code to work (i.e. emit top ten from a mapper).

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