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https://issues.apache.org/jira/browse/HADOOP-2120?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13109001#comment-13109001
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Ranadip commented on HADOOP-2120:
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> hadoop fs -get dir/* - > out
> has the same behavior, no ?
Not exactly same I think. In this case, out is a file on the local filesystem
while -getmerge is supposed to create the merged file on the hdfs.
Of course we can still achieve that doing something like
hadoop fs -get dir/* - | hadoop fs -put - dir/dest
> dfs -getMerge does not do what it says it does
> ----------------------------------------------
>
> Key: HADOOP-2120
> URL: https://issues.apache.org/jira/browse/HADOOP-2120
> Project: Hadoop Common
> Issue Type: Bug
> Components: documentation, fs
> Affects Versions: 0.14.3
> Environment: All
> Reporter: Milind Bhandarkar
> Labels: newbie
>
> dfs -getMerge, which calls FileUtil.CopyMerge, contains this javadoc:
> {code}
> Get all the files in the directories that match the source file pattern
> * and merge and sort them to only one file on local fs
> * srcf is kept.
> {code}
> However, it only concatenates the set of input files, rather than merging
> them in sorted order.
> Ideally, the copyMerge should be equivalent to a map-reduce job with
> IdentityMapper and IdentityReducer with numReducers = 1. However, not having
> to run this as a map-reduce job has some advantages, since it increases
> cluster utilization during reduce phase.
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