Hi,

Is it possible to run a MapReduce job on a part of file on HDFS? The use case is using a single file on HDFS as a stream to store all log events of a particular kind. New data can grow on top while Map Reduce can process old data. Of course one option would be to copy part of data into a separate file and give that to MapReduce but I was wondering if that extra copy can be avoided.

Thanks,
Pankaj

IIRC you can do this, but MR had some issues if you passed it a
non-closed (but sync'd upon) file for splitting.

However, if you run into similar issues, try generating your own
splits over the big file via FileInputFormat#getSplits(…), which will
then work.

On Thu, Nov 1, 2012 at 4:50 AM, Pankaj Gupta <[EMAIL PROTECTED]> wrote:
> Hi,
>
> Is it possible to run a MapReduce job on a part of file on HDFS? The use case is using a single file on HDFS as a stream to store all log events of a particular kind. New data can grow on top while Map Reduce can process old data. Of course one option would be to copy part of data into a separate file and give that to MapReduce but I was wondering if that extra copy can be avoided.
>
> Thanks,
> Pankaj

--
Harsh J