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Re: how to model data based on "time bucket"
I think I didn't explain correct.
    I want to read from 2 table in context of 1 mapreduce job.
I mean I want to read one key from main table and scan range from another
in the same mapreduce job.I only found MultiTableOutputFormat and there is
no MultiTableInputFormat. Is there any workaround to read from 2 tables
from one mapreduce?
   By the way I can use bulkloading to prevent hotspots and it gives
capabilities of  fast scan.

Thansk
Oleg.
On Mon, Jan 28, 2013 at 7:24 PM, Rodrigo Ribeiro <
[EMAIL PROTECTED]> wrote:

> Yes, it's possible,
> Check this solution:
>
> http://stackoverflow.com/questions/11353911/extending-hadoops-tableinputformat-to-scan-with-a-prefix-used-for-distribution
>
> On Mon, Jan 28, 2013 at 2:07 PM, Oleg Ruchovets <[EMAIL PROTECTED]
> >wrote:
>
> >  Yes.
> > This is very interesting approach.
> >
> >        Is it possible to read from main key and scan from another using
> > map/reduce? I don't want to read from single client. I use hbase version
> > 0.94.2.21.
> >
> > Thanks
> > Oleg.
> >
> >
> > On Mon, Jan 28, 2013 at 6:27 PM, Rodrigo Ribeiro <
> > [EMAIL PROTECTED]> wrote:
> >
> > > In the approach that i mentioned, you would need a table to retrieve
> the
> > > time of a certain event(if this information can retrieve in another
> way,
> > > you may ignore this table). It would be like you posted:
> > > event_id | time
> > > ============> > > event1 | 10:07
> > > event2 | 10:10
> > > event3 | 10:12
> > > event4 | 10:20
> > >
> > > And a secundary table would be like:
> > > rowkey
> > > ==========> > > 10:07:event1
> > > 10:10:event2
> > > 10:12:event3
> > > 10:20:event4
> > >
> > > That way, for your first example, you first retrieve the time of the
> > > "event1" on the main table, and then scan starting from his position on
> > the
> > > secondary table("10:07:event1"), until the end of the window.
> > > In this case(T=7) the scan will range ["10:07:event1", "10:05").
> > >
> > > As Michel Segel mentioned, there is a hotspot problem on insertion
> using
> > > this approach alone.
> > > Using multiples buckets(could be a hash from the eventId) would
> > distribute
> > > it better, but requires to scan on all buckets from the second table to
> > get
> > > all events of the window of time.
> > >
> > > Assuming you use 3 buckets, it would look like:
> > > rowkey
> > > ==========> > > *1_*10:07:event1
> > > *2_*10:10:event2
> > > *3_*10:12:event3
> > > *2_*10:20:event4
> > >
> > > The scans would be: ["*1*_10:07:event1", "1_10:15"),
> ["*2*_10:07:event1",
> > > "2_10:15"), and ["*3*_10:07:event1", "3_10:15"), you can then combine
> the
> > > results.
> > >
> > > Hope it helps.
> > >
> > > On Mon, Jan 28, 2013 at 12:49 PM, Oleg Ruchovets <[EMAIL PROTECTED]
> > > >wrote:
> > >
> > > > Hi Rodrigo.
> > > >   Can you please explain in more details your solution.You said that
> I
> > > will
> > > > have another table. How many table will I have? Will I have 2 tables?
> > > What
> > > > will be the schema of the tables?
> > > >
> > > > I try to explain what I try to achive:
> > > >     I have ~50 million records like {time|event}. I want to put the
> > data
> > > in
> > > > Hbase in such way :
> > > >     events of time X and all events what was after event X during
> time
> > > > T minutes (for example during 7 minutes).
> > > > So I will be able to scan all table and get groups like:
> > > >
> > > >   {event1:10:02} corresponds to events {event2:10:03} ,
> {event3:10:05}
> > ,
> > > > {event4:10:06}
> > > >   {event2:10:30} correnponds to events {events5:10:32} ,
> > {event3:10:33} ,
> > > > {event3:10:36}.
> > > >
> > > > Thanks
> > > > Oleg.
> > > >
> > > >
> > > > On Mon, Jan 28, 2013 at 5:17 PM, Rodrigo Ribeiro <
> > > > [EMAIL PROTECTED]> wrote:
> > > >
> > > > > You can use another table as a index, using a rowkey like
> > > > > '{time}:{event_id}', and then scan in the range ["10:07", "10:15").
> > > > >
> > > > > On Mon, Jan 28, 2013 at 10:06 AM, Oleg Ruchovets <