Hi Lin

The default values for all the properties are in
core-default.xml
hdfs-default.xml and
mapred-default.xml


Regards
Bejoy KS


On Tue, Sep 11, 2012 at 5:06 PM, Jason Yang <lin.yang.jason@gmail.com> wrote:
Hi, Bejoy

Thanks for you reply.

where could I find the default value of mapred.reduce.tasks ? I have checked the core-site.xml, hdfs-site.xml and mapred-site.xml, but I haven't found it.


2012/9/11 Bejoy Ks <bejoy.hadoop@gmail.com>
Hi Lin

The default value for number of reducers is 1

<name>mapred.reduce.tasks</name>
  <value>1</value>

It is not determined by data volume. You need to specify the number of reducers for your mapreduce jobs as per your data volume.

Regards
Bejoy KS

On Tue, Sep 11, 2012 at 4:53 PM, Jason Yang <lin.yang.jason@gmail.com> wrote:
Hi, all

I was wondering what's the default number of reducer if I don't set it in configuration?

Will it change dynamically according to the output volume of Mapper?

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YANG, Lin





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YANG, Lin