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HBase >> mail # user >> Understanding scan behaviour


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Mohit Anchlia 2013-03-28, 04:15
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Ted Yu 2013-03-28, 04:22
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ramkrishna vasudevan 2013-03-28, 04:23
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ramkrishna vasudevan 2013-03-28, 04:23
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Mohit Anchlia 2013-03-28, 14:38
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Jean-Marc Spaggiari 2013-03-28, 14:53
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Mohit Anchlia 2013-03-28, 15:17
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Jean-Marc Spaggiari 2013-03-28, 15:26
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Mohit Anchlia 2013-03-28, 16:02
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Re: Understanding scan behaviour
Take a look at the following in
hbase-server/src/main/ruby/shell/commands/scan.rb
(trunk)

  hbase> scan 't1', {FILTER => "(PrefixFilter ('row2') AND
    (QualifierFilter (>=, 'binary:xyz'))) AND (TimestampsFilter ( 123,
456))"}

Cheers

On Thu, Mar 28, 2013 at 9:02 AM, Mohit Anchlia <[EMAIL PROTECTED]>wrote:

> I see then I misunderstood the behaviour. My keys are id + timestamp so
> that I can do a range type search. So what I really want is to return a row
> where id matches the prefix. Is there a way to do this without having to
> scan large amounts of data?
>
>
>
> On Thu, Mar 28, 2013 at 8:26 AM, Jean-Marc Spaggiari <
> [EMAIL PROTECTED]> wrote:
>
> > Hi Mohit,
> >
> > "+" ascii code is 43
> > "9" ascii code is 57.
> >
> > So "+9" is coming after "++". If you don't have any row with the exact
> > key "+++++", HBase will look for the first one after this one. And in
> > your case, it's +9hC\xFC\x82s\xABL3\xB3B\xC0\xF9\x87\x03\x7F\xFF\xF.
> >
> > JM
> >
> > 2013/3/28 Mohit Anchlia <[EMAIL PROTECTED]>:
> > > My understanding is that the row key would start with +++++ for
> instance.
> > >
> > > On Thu, Mar 28, 2013 at 7:53 AM, Jean-Marc Spaggiari <
> > > [EMAIL PROTECTED]> wrote:
> > >
> > >> Hi Mohit,
> > >>
> > >> I see nothing wrong with the results below. What would I have
> expected?
> > >>
> > >> JM
> > >>
> > >> 2013/3/28 Mohit Anchlia <[EMAIL PROTECTED]>:
> > >>  > I am running 92.1 version and this is what happens.
> > >> >
> > >> >
> > >> > hbase(main):003:0> scan 'SESSIONID_TIMELINE', {LIMIT => 1, STARTROW
> =>
> > >> > 'sdw0'}
> > >> > ROW                                                  COLUMN+CELL
> > >> >  s\xC1\xEAR\xDF\xEA&\x89\x91\xFF\x1A^\xB6d\xF0\xEC\x
> > >> > column=SID_T_MTX:\x00\x00Rc, timestamp=1363056261106,
> > >> > value=PAGE\x09\x091363056252990\x09\x09/
> > >> >  7F\xFF\xFE\xC2\xA3\x84Z\x7F
> > >> >
> > >> > 1 row(s) in 0.0450 seconds
> > >> > hbase(main):004:0> scan 'SESSIONID_TIMELINE', {LIMIT => 1, STARTROW
> =>
> > >> > '------'}
> > >> > ROW                                                  COLUMN+CELL
> > >> >  -\xA1\xAF>r\xBD\xE2L\x00\xCD*\xD7\xE8\xD6\x1Dk\x7F\
> > >> > column=SID_T_MTX:\x00\x00hF, timestamp=1363384706714,
> > >> > value=PAGE\x09239923973\x091363384698919\x09/
> > >> >  xFF\xFE\xC2\x8F\xF0\xC1\xBF
> > >> >   row(s) in 0.0500 seconds
> > >> > hbase(main):005:0> scan 'SESSIONID_TIMELINE', {LIMIT => 1, STARTROW
> =>
> > >> > '++++'}
> > >> > ROW                                                  COLUMN+CELL
> > >> >  +9hC\xFC\x82s\xABL3\xB3B\xC0\xF9\x87\x03\x7F\xFF\xF
> > >> > column=SID_T_MTX:\x00\x00<2, timestamp=1364404155426,
> > >> > value=PAGE\x09\x091364404145275\x09 \x09/
> > >> >  E\xC2S-\x08\x1F
> > >> > 1 row(s) in 0.0640 seconds
> > >> > hbase(main):006:0>
> > >> >
> > >> >
> > >> > On Wed, Mar 27, 2013 at 9:23 PM, ramkrishna vasudevan <
> > >> > [EMAIL PROTECTED]> wrote:
> > >> >
> > >> >> Same question, same time :)
> > >> >>
> > >> >> Regards
> > >> >> Ram
> > >> >>
> > >> >> On Thu, Mar 28, 2013 at 9:53 AM, ramkrishna vasudevan <
> > >> >> [EMAIL PROTECTED]> wrote:
> > >> >>
> > >> >> > Could you give us some more insights on this?
> > >> >> > So you mean when you set the row key as 'azzzaaa', though this
> row
> > >> does
> > >> >> > not exist, the scanner returns some other row?  Or it is giving
> > you a
> > >> row
> > >> >> > that does not exist?
> > >> >> >
> > >> >> > Or you mean it is doing a full table scan?
> > >> >> >
> > >> >> > Which version of HBase and what type of filters are you using?
> > >> >> > Regards
> > >> >> > Ram
> > >> >> >
> > >> >> >
> > >> >> > On Thu, Mar 28, 2013 at 9:45 AM, Mohit Anchlia <
> > >> [EMAIL PROTECTED]
> > >> >> >wrote:
> > >> >> >
> > >> >> >> I have key in the form of "hashedid + timestamp" but when I run
> > scan
> > >> I
> > >> >> get
> > >> >> >> rows for almost every value. For instance if I run scan for
> > 'azzzaaa'
> > >> >> that
> > >> >> >> doesn't even exist even then I get the results.
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Mohit Anchlia 2013-03-28, 17:17
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Ted Yu 2013-03-28, 17:23
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Li, Min 2013-03-29, 05:48
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ramkrishna vasudevan 2013-03-29, 06:20
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James Taylor 2013-03-29, 07:44
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Mohit Anchlia 2013-03-29, 16:31
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Asaf Mesika 2013-03-30, 13:55
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Mohit Anchlia 2013-03-30, 15:25
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Ted Yu 2013-03-30, 16:37