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Hadoop InputFormat - Processing large number of small files

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I have a use case wherein I need to process huge set of files stored in HDFS. Those files are non-splittable and they need to be processed as a whole. Here, I have the following question for which I need answers to proceed further in this.

  1. I wish to schedule the map process in task tracker where data is already available. How can I do it? Currently, I have a file that contains list of filenames. Each map get one line of it via NLineInputFormat. The map process then accesses the file via FSDataInputStream and work with it. Is there a way to ensure this map process is running on the node where the file is available?

  2. Since the files are not large and it can be called as small files by hadoop standard. Now, I came across CombineFileInputFormat that can process more than one file in a single map process. What I need here is a format that can process more than one files in a single map but does not have to read the files, and either in key or value, it has the filenames. In map process then, I can run a loop to process these files. Any help?

  3. Any other alternatives?

posted Aug 20, 2014 by Tarun Singhal

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