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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Tall good with Scans, Wide good with Gets???
Date Wed, 22 Jan 2014 23:15:27 GMT
You're welcome.


On Wed, Jan 22, 2014 at 3:03 PM, Tianying Chang <tychang@gmail.com> wrote:

> Thanks Ted, This jira helped me to understand that claim much better now.
>
>
> On Wed, Jan 22, 2014 at 1:10 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>
> > For the follow-on question of #1, see HBASE-9488 : small scan.
> >
> > Cheers
> >
> >
> > On Wed, Jan 22, 2014 at 10:30 AM, Tianying Chang <tychang@gmail.com>
> > wrote:
> >
> > > 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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