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Date: Tue, 11 Sep 2012 17:13:56 +0530
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 <CACD21EMB52Vn9LPeyDoS5kOFTvRZ0gymUU8UC86iEVED8O3txQ@mail.gmail.com>
Subject: Re: what's the default reducer number?
From: Bejoy Ks <bejoy.hadoop@gmail.com>
To: user@hadoop.apache.org
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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?
>>>
>>> --
>>> YANG, Lin
>>>
>>>
>>
>
>
> --
> YANG, Lin
>
>

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<div>Hi Lin</div><div><br></div>The default values for all the properties a=
re in<div>core-default.xml</div><div>hdfs-default.xml and</div><div>mapred-=
default.xml</div><div><br></div><div><br></div><div>Regards</div><div>Bejoy=
 KS<br>
<div><br><br><div class=3D"gmail_quote">On Tue, Sep 11, 2012 at 5:06 PM, Ja=
son Yang <span dir=3D"ltr">&lt;<a href=3D"mailto:lin.yang.jason@gmail.com" =
target=3D"_blank">lin.yang.jason@gmail.com</a>&gt;</span> wrote:<br><blockq=
uote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc =
solid;padding-left:1ex">
Hi, Bejoy<div><br></div><div>Thanks for you reply.</div><div><br></div><div=
>where could I find the default value of mapred.reduce.tasks ? I have check=
ed the core-site.xml, hdfs-site.xml and mapred-site.xml, but I haven&#39;t =
found it.<div>
<div class=3D"h5"><br>

<br><div class=3D"gmail_quote">2012/9/11 Bejoy Ks <span dir=3D"ltr">&lt;<a =
href=3D"mailto:bejoy.hadoop@gmail.com" target=3D"_blank">bejoy.hadoop@gmail=
.com</a>&gt;</span><br><blockquote class=3D"gmail_quote" style=3D"margin:0 =
0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">


Hi Lin<div><br></div><div>The default value for number of reducers is 1</di=
v><div><br></div><div><div>&lt;name&gt;mapred.reduce.tasks&lt;/name&gt;</di=
v><div>=A0 &lt;value&gt;1&lt;/value&gt;</div><div><br></div><div>It is not =
determined by data volume. You need to specify the number of reducers for y=
our mapreduce jobs as per your data volume.</div>



<div><br></div><div>Regards</div><span><font color=3D"#888888"><div>Bejoy K=
S</div></font></span><div><div><br><div class=3D"gmail_quote">On Tue, Sep 1=
1, 2012 at 4:53 PM, Jason Yang <span dir=3D"ltr">&lt;<a href=3D"mailto:lin.=
yang.jason@gmail.com" target=3D"_blank">lin.yang.jason@gmail.com</a>&gt;</s=
pan> wrote:<br>



<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">Hi, all<div><br></div><div>I was wondering w=
hat&#39;s the default number of reducer if I don&#39;t set it in configurat=
ion?</div>



<div><br></div><div>Will it change dynamically according to the output volu=
me of Mapper?</div><span><font color=3D"#888888">

<div><div><br></div>-- <br><div>YANG, Lin</div><br>
</div>
</font></span></blockquote></div><br></div></div></div>
</blockquote></div><br><br clear=3D"all"><div><br></div></div></div><span c=
lass=3D"HOEnZb"><font color=3D"#888888">-- <br><div>YANG, Lin</div><br>
</font></span></div>
</blockquote></div><br></div></div>

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