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From Ted Yu <yuzhih...@gmail.com>
Subject Re: HBase load distribution vs. scan efficiency
Date Mon, 20 Jan 2014 02:53:34 GMT
Bill:
See  http://blog.sematext.com/2012/04/09/hbasewd
-avoid-regionserver-hotspotting-despite-writing-records-with-sequential-keys/

FYI


On Sun, Jan 19, 2014 at 4:02 PM, Bill Q <bill.q.hdp@gmail.com> wrote:

> Hi Amit,
> Thanks for the reply.
>
> If I understand your suggestion correctly, and assuming we have 100 region
> servers, I would have to do 100 scans to merge reads if I want to pull any
> data for a specific date. Is that correct? Is the 100 scans the most
> efficient way to deal with this issue?
>
> Any thoughts?
>
> Many thanks.
>
>
> Bill
>
>
> On Sun, Jan 19, 2014 at 4:02 PM, Amit Sela <amits@infolinks.com> wrote:
>
> > If you'll use bulk load to insert your data you could use the date as key
> > prefix and choose the rest of the key in a way that will split each day
> > evenly. You'll have X regions for Evey day >> 14X regions for the two
> weeks
> > window.
> > On Jan 19, 2014 8:39 PM, "Bill Q" <bill.q.hdp@gmail.com> wrote:
> >
> > > Hi,
> > > I am designing a schema to host some large volume of data over HBase.
> We
> > > collect daily trading data for some markets. And we run a moving window
> > > analysis to make predictions based on a two weeks window.
> > >
> > > Since everybody is going to pull the latest two weeks data every day,
> if
> > we
> > > put the date in the lead positions of the Key, we will have some hot
> > > regions. So, we can use bucketing (date to mode bucket number) approach
> > to
> > > deal with this situation. However, if we have 200 buckets, we need to
> run
> > > 200 scans to extract all the data in the last two weeks.
> > >
> > > My questions are:
> > > 1. What happens when each scan return the result? Will the scan result
> be
> > > sent to a sink  like place that collects and concatenate all the scan
> > > results?
> > > 2. Why having 200 scans might be a bad thing compared to have only 10
> > > scans?
> > > 3. Any suggestions to the design?
> > >
> > > Many thanks.
> > >
> > >
> > > Bill
> > >
> >
>

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