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Date: Thu, 21 Mar 2013 11:06:56 +0400
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 <CAMe0HzQRZiSJGpkTH20xxAzKi--YA+kwUzBFMwK+meN_hOzGDw@mail.gmail.com>
Subject: Re: Combiner in Secondary Sort
From: Fatih Haltas <fatih.haltas@nyu.edu>
To: "user@hadoop.apache.org" <user@hadoop.apache.org>
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Thanks very much Harsh


On Thu, Mar 21, 2013 at 4:50 AM, Harsh J <harsh@cloudera.com> wrote:

> You're probably running into
> https://issues.apache.org/jira/browse/MAPREDUCE-3310. There was also a
> discussion on this IIRC but I cannot find the archive now. One aside
> mention on this from Chris is at
> http://search-hadoop.com/m/RH5AP11ob2o1.
>
> On Wed, Mar 20, 2013 at 6:10 PM, Fatih Haltas <fatih.haltas@nyu.edu>
> wrote:
> > Hi Everyone,
> >
> > I am trying to implement Secondary Sort Algorithm on mydata. But I am
> having
> > a trouble with my Combiner.
> >
> > When I donot use Combiner, grouping is done well, I mean one reduce task
> is
> > running for every pair, sharing the same first element.
> >
> > However, when I set Combiner as Reducer class itself, grouping in the
> > Combiner is not done according to my custom GroupingComparator class
> though.
> >
> > How can i overrride Combiner class's grouping?
> > Or, is there any diagram, showing the sequence of workflow(both in map
> > phase, calls of mapper classes and calls of combiner classes and so on
> > sequentially) in more detailed?
> >
> > Thanks very much.
>
>
>
> --
> Harsh J
>

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<div dir=3D"ltr">Thanks very much Harsh</div><div class=3D"gmail_extra"><br=
><br><div class=3D"gmail_quote">On Thu, Mar 21, 2013 at 4:50 AM, Harsh J <s=
pan dir=3D"ltr">&lt;<a href=3D"mailto:harsh@cloudera.com" target=3D"_blank"=
>harsh@cloudera.com</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">You&#39;re probably running into<br>
<a href=3D"https://issues.apache.org/jira/browse/MAPREDUCE-3310" target=3D"=
_blank">https://issues.apache.org/jira/browse/MAPREDUCE-3310</a>. There was=
 also a<br>
discussion on this IIRC but I cannot find the archive now. One aside<br>
mention on this from Chris is at<br>
<a href=3D"http://search-hadoop.com/m/RH5AP11ob2o1" target=3D"_blank">http:=
//search-hadoop.com/m/RH5AP11ob2o1</a>.<br>
<div><div class=3D"h5"><br>
On Wed, Mar 20, 2013 at 6:10 PM, Fatih Haltas &lt;<a href=3D"mailto:fatih.h=
altas@nyu.edu">fatih.haltas@nyu.edu</a>&gt; wrote:<br>
&gt; Hi Everyone,<br>
&gt;<br>
&gt; I am trying to implement Secondary Sort Algorithm on mydata. But I am =
having<br>
&gt; a trouble with my Combiner.<br>
&gt;<br>
&gt; When I donot use Combiner, grouping is done well, I mean one reduce ta=
sk is<br>
&gt; running for every pair, sharing the same first element.<br>
&gt;<br>
&gt; However, when I set Combiner as Reducer class itself, grouping in the<=
br>
&gt; Combiner is not done according to my custom GroupingComparator class t=
hough.<br>
&gt;<br>
&gt; How can i overrride Combiner class&#39;s grouping?<br>
&gt; Or, is there any diagram, showing the sequence of workflow(both in map=
<br>
&gt; phase, calls of mapper classes and calls of combiner classes and so on=
<br>
&gt; sequentially) in more detailed?<br>
&gt;<br>
&gt; Thanks very much.<br>
<br>
<br>
<br>
</div></div>--<br>
Harsh J<br>
</blockquote></div><br></div>

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