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https://issues.apache.org/jira/browse/MAPREDUCE-2208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13607716#comment-13607716
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Marcelo Elias Del Valle commented on MAPREDUCE-2208:
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Christian, this is a valid concern. Actually, when I created the first version
of this input format, I had chosen to have the CSV line numbers as the keys.
Indeed, it worked well until I tested it on a cluster (amazon EMR with 15
instances). When I did, I realized the line numbers wasn't a good key, as it
wouldn't get the right results among cluster nodes.
I fixed that to use the file position as input key, just as NLineInputFormat
does
(http://hadoop.apache.org/docs/current/api/org/apache/hadoop/mapred/lib/NLineInputFormat.html)
I have tested it a lot and so far I found no problems. However, if you find
some problem I didn't see, please tell me, as I would be very interested in
fixing it.
> Flexible CSV text parser InputFormat
> ------------------------------------
>
> Key: MAPREDUCE-2208
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2208
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Reporter: Lance Norskog
> Priority: Trivial
> Attachments: CSVTextInputFormat.java, TestCSVTextFormat.java
>
>
> CSVTextInputFormat is a configurable CSV parser tuned to most of the
> csv-style datasets I've found. The Hadoop samples I've seen all
> FileInputFormat and Mapper<LongWritable,Text>. They drop the Longwritable key
> and parse the Text value as a CSV line. But, they are all custom-coded for
> the format.
> CSVTextInputFormat takes any csv-encoded file and rearrange the fields into
> the format required by a Mapper. You can drop fields & rearrange them. There
> is also a random sampling option to make training/test runs easier.
> Attached are CSVTextInputFormat.java and a unit test for it. Both go into
> org.apache.hadoop.mapreduce.lib.input under src/java and test/mapred/src.
> This is compiled against hadoop-0.0.20.
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