How to insert a line to the beginning of a file in HDFS

Asked Jan 24 '14 at 05:06

Active Jan 24 '14 at 12:44

Viewed 787 times

I have a Hadoop program in which I need to add a couple of line to the beginning of the reducer's output file (when it's done) in my Java program. I'm using the following code

 RandomAccessFile f = new RandomAccessFile(new File("/user/hzakerza/graph/output9/part-r-00000"), "rw");
 f.seek(0);             
 f.writeChars("some line");
 f.close();

However it gives me an error that the file does not exist. How can I insert a few lines to this file within my Java program?

edited Jan 24 '14 at 12:44

Simulant

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asked Jan 24 '14 at 05:06

HHH

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"Append" specifically implies _add to the end._ Just sayin'. – Matt Ball Jan 24 '14 at 05:08
Are you doing this after the job returns? Is this in your driver file? – Suvarna Pattayil Jan 24 '14 at 06:50
yes, when the reducer is done. – HHH Jan 24 '14 at 07:21
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`RandomAccessFile` may be accessing the local filesystem and not HDFS – Suvarna Pattayil Jan 24 '14 at 08:38
Btw check these links, http://stackoverflow.com/questions/5769394/why-doesnt-hadoop-file-system-support-random-i-o http://mail-archives.apache.org/mod_mbox/hadoop-common-user/200811.mbox/%3C4aa34eb70811131511h4382bf46rfb65ef0f86e755b@mail.gmail.com%3E – Suvarna Pattayil Jan 24 '14 at 08:39

How to insert a line to the beginning of a file in HDFS

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