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MapReduce >> mail # user >> reducer tasks start time issue


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reducer tasks start time issue
Hi guys,

Supposing in a Hadoop job, there are both mappers and reducers. My question
is, reducer tasks cannot begin until all mapper tasks complete? If so, why
designed in this way?

thanks in advance,
Lin
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB