Mohith, It is always better to go with start row and end row if you are knowing what are they. Just add one byte more to the actual end row (inclusive row) and form the end key. This will narrow down the search.
Remeber the byte comparison is the way that HBase scans. Regards Ram On Fri, Mar 29, 2013 at 11:18 AM, Li, Min <[email protected]> wrote: > Hi, Mohit, > > Try using ENDROW. STARTROW&ENDROW is much faster than PrefixFilter. > > "+" ascii code is 43 > "," ascii code is 44 > > scan 'SESSIONID_TIMELINE', {LIMIT => 1,STARTROW => '++++', ENDROW=>'+++,'} > > Min > > -----Original Message----- > From: Mohit Anchlia [mailto:[email protected]] > Sent: Friday, March 29, 2013 1:18 AM > To: [email protected] > Subject: Re: Understanding scan behaviour > > 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? > > > > >> >> >> > > > > >> >> > > > > > >> >> > > > > > >> >> > > > > >> > > > > > > > > > >
