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HDFS >> mail # user >> Re: How to maintain record boundaries


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Re: How to maintain record boundaries
Shreya,

This has been asked several times before, and the way it is handled by
TextInputFormats (for one example) is explained at
http://wiki.apache.org/hadoop/HadoopMapReduce in the Map section. If
you are writing a custom reader, feel free to follow the same steps -
you basically need to seek over to next blocks for an end-record
marker and not limit yourself to just one-block reads.

All input formats provided in MR handle this already for you, and you
needn't worry about this unless you're implementing a whole new reader
from scratch.

On Fri, May 11, 2012 at 5:45 PM,  <[EMAIL PROTECTED]> wrote:
> Hi
>
> When we store data into HDFS, it gets broken into small pieces and distributed across the cluster based on Block size for the file.
> While processing the data using MR program I want a particular record as a whole without it being split across nodes, but the data has already been split and stored in HDFS when I loaded the data.
> How would I make sure that my record doesn't get split, how would my Input format make a difference now ?
>
> Regards
> Shreya
>
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--
Harsh J
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB