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https://issues.apache.org/jira/browse/HADOOP-1194?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12486213
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Arun C Murthy commented on HADOOP-1194:
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Runping,
'mapred.compress.map.output' is the boolean which controls whether map outputs
are compressed. If set to true (@see MapTask.java:279) the
'mapred.output.compression.type' can be used to specify RECORD/BLOCK - this
defaults to SequenceFile's compression-type i.e. 'io.seqfile.compression.type'
which defaults to RECORD compression. (@see
JobConf.getMapOutputCompressionType).
Does this help? Or do you propose we change JobConf.getMapOutputCompressionType
to return RECORD if 'mapred.output.compression.type' is unset i.e. do not use
io.seqfile.compression.type? Thanks for the clarification...
> map output should not do block level compression
> ------------------------------------------------
>
> Key: HADOOP-1194
> URL: https://issues.apache.org/jira/browse/HADOOP-1194
> Project: Hadoop
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.12.2
> Reporter: Runping Qi
>
> If the user sets to compress the map output, the compression style should be
> record level, not block level, since using block level compression for map
> outputs causes performance degragation significantly.
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