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From: Peter Haidinyak <phaidinyak@local.com>
To: "user@hbase.apache.org" <user@hbase.apache.org>
Date: Thu, 20 Jan 2011 08:41:07 -0800
Subject: RE: Scan (Start Row, End Row) vs Scan (Row)
Thread-Topic: Scan (Start Row, End Row) vs Scan (Row)
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Question, does HBase stop scanning after it hits the end row? I thought it =
does.

Thanks

-Pete

-----Original Message-----
From: Jonathan Gray [mailto:jgray@fb.com]=20
Sent: Thursday, January 20, 2011 8:09 AM
To: user@hbase.apache.org
Subject: RE: Scan (Start Row, End Row) vs Scan (Row)

The best way to do this is as Friso describes, using the existing stopRow p=
arameter in Scan.

There is another way to do it with startRow + a filter.  There is a PrefixF=
ilter which could be used here.  Looking at the code, it seems as though th=
e PrefixFilter does an early out and stops the scan once passed the prefix.

If not, you can wrap any filter in a WhileMatchFilter.  That wrapping filte=
r will make it so once the underlying filter fails once, all further things=
 will fail and the scan will early out.

JG

> -----Original Message-----
> From: Friso van Vollenhoven [mailto:fvanvollenhoven@xebia.com]
> Sent: Thursday, January 20, 2011 12:45 AM
> To: <user@hbase.apache.org>
> Subject: Re: Scan (Start Row, End Row) vs Scan (Row)
>=20
> Performing a scan with
>=20
> start row =3D 20100809041500_abd
> end row =3D 20100809041500_abe
>=20
> will give you just that. The end row is exclusive, so it will only return=
 rows
> with VAR1 =3D abd. You need to compute the 'abe' yourself, though (which =
is
> basically taking 'abd' and increasing the right most byte by 1 unless it'=
s at max
> byte value, then set it to 0 and increase the byte left to that by 1, etc=
.). There
> is no scan method that has 'starts with' semantics, AFAIK.
>=20
> See here:
> http://hbase.apache.org/docs/r0.89.20100924/apidocs/org/apache/hadoop/
> hbase/client/Scan.html#Scan(byte[],
> byte[])<http://hbase.apache.org/docs/r0.89.20100924/apidocs/org/apache/
> hadoop/hbase/client/Scan.html#Scan(byte%5B%5D,%20byte%5B%5D)>
>=20
>=20
> Friso
>=20
>=20
>=20
>=20
> On 20 jan 2011, at 09:22, Shuja Rehman wrote:
>=20
> Hi
> Consider the following scenario.
>=20
> Row Key  Format =3D DATETIME_VAR1_VAR2 (where var1 and var2 have fixed
> lengths)
>=20
> and example data could be
>=20
> 20100809041500_abc_xyz
> 20100809041500_abc_xyw
> 20100809041500_abc_xyc
> *20100809041500_abd_xyz*
> 20100809041500_abd_xyw
> 20100809041500_abf_xyz
> ...
>=20
> Now if i want to get the rows which only have this row key
> 20100809041500_abd then is there anyway to achieve through scan without
> using filter because if i use filter scan(startrow, filter) where
> startrow=3D"20100809041500_abd" then it will scan whole table from start =
key
> to end of table. i want to just scan that part of table which i require. =
So if
> there is any method like this
>=20
> scan(row)  where row =3D"20100809041500_abd"  and it just return the
> following results
>=20
> 20100809041500_abd_xyz
> 20100809041500_abd_xyw
>=20
> Kindly let me know whether it is achievable or not?
> thnx
> --
> Regards
> Shuja-ur-Rehman Baig
> <http://pk.linkedin.com/in/shujamughal>