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From Tianying Chang <tych...@gmail.com>
Subject Re: Tall good with Scans, Wide good with Gets???
Date Wed, 22 Jan 2014 18:30:36 GMT
Ted, Thanks for link!

1. the post said "Get will pread from HDFS where Scan will seek and read
under lock (and only fall back to pread when it notices contention on the
hfile)." It seems pread  is for highly concurrent small readers.  So this
brings me a new question: does this mean that if my scan startKey/endKey
only covers 10 rows, it is faster to run a getMultiple()???


2. Still confused why Tall is good for Scans, wide is good for Gets? I
thought the underlying storage is stored in KV. so tall or wide shouldn't
matter, right?

Thanks
Tian-Ying


On Wed, Jan 22, 2014 at 10:12 AM, Ted Yu <yuzhihong@gmail.com> wrote:

> See
>
> http://search-hadoop.com/m/nAAad2wRi03/Is+get+a+private+case+of+scan&subj=Re+Is+get+a+private+case+of+scan+
>
> Cheers
>
>
> On Wed, Jan 22, 2014 at 10:09 AM, Tianying Chang <tychang@gmail.com>
> wrote:
>
> > Hi,
> >
> > I watched this youtube video http://www.youtube.com/watch?v=_HLoH_PgrLkby
> > Lars George. It is really good one!
> >
> > I just have one thing still cannot understand. It said Tall is good for
> > Scan, Wide is good for Get. My understanding is that Scan and Get is
> using
> > the same code underlying. It first seek to the specific kv, check data,
> > after done, then do next() . Considering the underlying storage is same
> for
> > wide or tall, and the code to do scan/get is the same. why Tall is good
> for
> > Scan, and wide is good for Get?
> >
> > Does anyone know why? This really puzzles me.
> >
> > Thanks a lot!
> > Tian-Ying
> >
>

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