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From Abhishek Pratap Singh <manu.i...@gmail.com>
Subject Re: Zero Byte file in HDFS
Date Mon, 26 Mar 2012 21:41:53 GMT
Thanks Bejoy for this input, Does this merging will combine all the small
files to least block size for the very first mappers of the hive job?
Well i ll explore on this, my interest on deleting the zero byte files from
HDFS comes from reducing the cost of Bookkeeping these files in system. The
metadata of any files in HDFS occupy approx 150kb space, considering
thousand or millions of zero byte file in HDFS will cost a lot.


On Mon, Mar 26, 2012 at 2:27 PM, Bejoy KS <bejoy.hadoop@gmail.com> wrote:

> Hi Abshikek
>       I can propose a better solution. Enable merge in hive. So that the
> smaller files would be merged to at lest the hdfs block size(your choice)
> and would benefit subsequent hive jobs on the same.
> Regards
> Bejoy KS
> Sent from handheld, please excuse typos.
> -----Original Message-----
> From: Abhishek Pratap Singh <manu.infy@gmail.com>
> Date: Mon, 26 Mar 2012 14:20:18
> To: <common-user@hadoop.apache.org>; <user@hive.apache.org>
> Reply-To: common-user@hadoop.apache.org
> Subject: Zero Byte file in HDFS
> Hi All,
> I was just going through the implementation scenario of avoiding or
> deleting Zero byte file in HDFS. I m using Hive partition table where the
> data in partition come from INSERT OVERWRITE command using the SELECT from
> few other tables.
> Sometimes 0 Byte files are being generated in those partitions and during
> the course of time the amount of these files in the HDFS will increase
> enormously, decreasing the performance of hadoop job on that table /
> folder. I m looking for best way to avoid generation or deleting the zero
> byte file.
> I can think of few ways to implement this
> 1) Programmatically using the Filesystem object and cleaning the zero byte
> file.
> 2) Using Hadoop fs and Linux command combination to identify the zero byte
> file and delete it.
> 3) LazyOutputFormat (Applicable in Hadoop based custom jobs).
> Kindly guide on efficient ways to achieve the same.
> Regards,
> Abhishek

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