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From: anil gupta <anilgupta84@gmail.com>
Date: Sun, 25 Aug 2013 21:08:30 -0700
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 <CAF1+Vs_cg9=nsBvL8rSrNdi-YF3kqPoCDXfLPT98NMrfJTfdBg@mail.gmail.com>
Subject: Re: Mapper and Reducer takes longer than usual for a HBase table
 aggregation task
To: "common-user@hadoop.apache.org" <user@hadoop.apache.org>
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Hi Pavan,

Standalone cluster? How many RS you are running?What are you trying to
achieve in MR? Have you tried increasing scanner caching?
Slow is very theoretical unless we know some more details of your stuff.

~Anil


On Sun, Aug 25, 2013 at 5:52 PM, =C0=EE=BA=E9=D6=D2 <lhztop@hotmail.com> wr=
ote:

> You need release your map code here to analyze the question. generally,
> when map/reduce hbase,  scanner with filter(s) is used. so the mapper cou=
nt
> is the hbase region count in your hbase table.
> As the reason why you reduce so slow, I guess, you have an disaster join
> on the three tables, which cause too many rows.
>
> =D3=DA 2013/8/26 4:36, Pavan Sudheendra =D0=B4=B5=C0:
>
>  Another Question, why does it indicate number of mappers as 1? Can i
>> change it so that multiple mappers perform computation?
>>
>
>


--=20
Thanks & Regards,
Anil Gupta

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<div dir=3D"ltr"><div><div>Hi Pavan,<br><br></div>Standalone cluster? How m=
any RS you are running?What are you trying to achieve in MR? Have you tried=
 increasing scanner caching?<br>Slow is very theoretical unless we know som=
e more details of your stuff.<br>

<br></div><div>~Anil<br></div><br></div><div class=3D"gmail_extra"><br><br>=
<div class=3D"gmail_quote">On Sun, Aug 25, 2013 at 5:52 PM, =C0=EE=BA=E9=D6=
=D2 <span dir=3D"ltr">&lt;<a href=3D"mailto:lhztop@hotmail.com" target=3D"_=
blank">lhztop@hotmail.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 need release your map code here to analy=
ze the question. generally, when map/reduce hbase, &nbsp;scanner with filte=
r(s) is used. so the mapper count is the hbase region count in your hbase t=
able.<br>


As the reason why you reduce so slow, I guess, you have an disaster join on=
 the three tables, which cause too many rows.<br>
<br>
=D3=DA 2013/8/26 4:36, Pavan Sudheendra =D0=B4=B5=C0:<div class=3D"HOEnZb">=
<div class=3D"h5"><br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
Another Question, why does it indicate number of mappers as 1? Can i change=
 it so that multiple mappers perform computation?<br>
</blockquote>
<br>
</div></div></blockquote></div><br><br clear=3D"all"><br>-- <br>Thanks &amp=
; Regards,<br>Anil Gupta
</div>

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