[
https://issues.apache.org/jira/browse/HADOOP-1440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12503622
]
Runping Qi commented on HADOOP-1440:
------------------------------------
That does not really address the problem this Jira tries to address:
In the reduce=None case, the user wants to control two things:
1. Whether the input files are splittable.
2. If it is set that the input files are not splitable, the number of the
output files must be the same as
that of input files, and the relative order of the input files is the same as
that of the corresponding
output files.
That is why I proposed to use the input filenames as the prefix for the output
filenames.
> JobClient should not sort input-splits
> --------------------------------------
>
> Key: HADOOP-1440
> URL: https://issues.apache.org/jira/browse/HADOOP-1440
> Project: Hadoop
> Issue Type: Improvement
> Components: mapred
> Affects Versions: 0.12.3
> Environment: All
> Reporter: Milind Bhandarkar
> Assignee: Milind Bhandarkar
> Fix For: 0.14.0
>
>
> Currently, the JobClient sorts the InputSplits returned by InputFormat in
> descending order, so that the map tasks corresponding to larger input-splits
> are scheduled first for execution than smaller ones. However, this causes
> problems in applications that produce data-sets partitioned similarly to the
> input partition with -reducer NONE.
> With -reducer NONE, map task i produces part-i. Howver, in the typical
> applications that use -reducer NONE it should produce a partition that has
> the same index as the input parrtition.
> (Of course, this requires that each partition should be fed in its entirety
> to a map, rather than splitting it into blocks, but that is a separate issue.)
> Thus, sorting input splits should be either controllable via a configuration
> variable, or the FileInputFormat should sort the splits and JobClient should
> honor the order of splits.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
