See javadoc of TimestampsFilter which reveals how you can narrow the scan:
* Note: Use of this filter overrides any time range/time stamp
* options specified using {@link
org.apache.hadoop.hbase.client.Get#setTimeRange(long, long)},
* {@link org.apache.hadoop.hbase.client.Scan#setTimeRange(long, long)}, {@link
org.apache.hadoop.hbase.client.Get#setTimeStamp(long)},
* or {@link org.apache.hadoop.hbase.client.Scan#setTimeStamp(long)}.
Answer to your second question is Yes.
On Thu, Mar 28, 2013 at 10:17 AM, Mohit Anchlia <[email protected]>wrote:
> Could the prefix filter lead to full tablescan? In other words is
> PrefixFilter applied after fetching the rows?
>
> Another question I have is say I have row key abc and abd and I search for
> row "abc", is it always guranteed to be the first key when returned from
> scanned results? If so I can alway put a condition in the client app.
>
> On Thu, Mar 28, 2013 at 9:15 AM, Ted Yu <[email protected]> wrote:
>
> > 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.
> > > > >> >> >>
> > > > >> >> >> Could someone help me understand what might be going on
> here?
> > > > >> >> >>
> > > > >> >> >
> > > > >> >> >
> > > > >> >>
> > > > >>
> > > >
> > >
> >
>
