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References: <CB87934D.27213%doug.meil@explorysmedical.com>
 <4F621E5F.7050605@gmail.com>
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Date: Thu, 15 Mar 2012 10:04:52 -0700 (PDT)
From: lars hofhansl <lhofhansl@yahoo.com>
Reply-To: lars hofhansl <lhofhansl@yahoo.com>
Subject: Re: Scan.addFamiliy reduces results
To: "user@hbase.apache.org" <user@hbase.apache.org>
In-Reply-To: <4F621E5F.7050605@gmail.com>
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Hi Peter,=0Afor HBase you have keep in mind that it is a sparse columnar (o=
r KeyValue) store: (rowkey, columnfamily, column, TS) -> value=0A=0AA scan =
only returns those KeyValues that match the scan. So when you set families =
on your scan you'll only get those rows for which the scan found any column=
s.=0A=0AMakes sense?=0A=0A-- Lars=0A=0A=0A=0A______________________________=
__=0A From: Peter Wolf <opus111@gmail.com>=0ATo: user@hbase.apache.org =0AS=
ent: Thursday, March 15, 2012 9:52 AM=0ASubject: Re: Scan.addFamiliy reduce=
s results=0A =0AThanks Doug,=0A=0AI had read that, and I just read it again=
.=A0 But I am missing something...=0A=0AWhy does adding a family reduce the=
 number of results?=A0 Is there an =0Aimplied filter of some form?=A0 Does =
addFamily add some constraint on =0Awhich rows are returned?=0A=0ANote that=
 all my rows *ought* to have values in all the families.=0A=0AThanks=0APete=
r=0A=0AOn 3/15/12 12:39 PM, Doug Meil wrote:=0A> re:=A0 "However, I am gett=
ing different number of results, depending on=0A> which families are added"=
=0A>=0A> Yes.=0A>=0A> I'd suggest you read this in the RefGuide.=0A>=0A> ht=
tp://hbase.apache.org/book.html#datamodel=0A>=0A>=0A>=0A>=0A>=0A> On 3/15/1=
2 12:08 PM, "Peter Wolf"<opus111@gmail.com>=A0 wrote:=0A>=0A>> Hi all,=0A>>=
=0A>> I am doing a scan on a table with multiple families.=A0 My code looks=
 like=0A>> this...=0A>>=0A>>=A0 =A0 =A0 =A0 =A0 Scan scan =3D new Scan(calc=
ulateStartRowKey(a),=0A>> calculateEndRowKey(b));=0A>>=0A>>=A0 =A0 =A0 =A0 =
=A0 scan.setCaching(10000);=0A>>=A0 =A0 =A0 =A0 =A0 Filter filter =3D new S=
ingleColumnValueFilter(xFamily, xColumn,=0A>> CompareFilter.CompareOp.EQUAL=
, Bytes.toBytes(x));=0A>>=A0 =A0 =A0 =A0 =A0 scan.setFilter(filter);=0A>>=
=A0 =A0 =A0 =A0 =A0 scan=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .addFamily=
(xFamily)=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .addFamily(yFamily)=0A>>=
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .addFamily(zFamily);=0A>>=0A>>=A0 =A0 =
=A0 =A0 =A0 ResultScanner scanner =3D hTable.getScanner(scan);=0A>>=0A>>=A0=
 =A0 =A0 =A0 =A0 Iterator<Result>=A0 it =3D scanner.iterator();=0A>>=A0 =A0=
 =A0 =A0 =A0 int resultCount =3D 0;=0A>>=A0 =A0 =A0 =A0 =A0 while (it.hasNe=
xt()) {=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Result result =3D it.next();=0A=
>>=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 resultCount++;=0A>>=A0 =A0 =A0 =A0 =
=A0 }=0A>>=0A>> However, I am getting different number of results, dependin=
g on which=0A>> families are added.=A0 For example these give different res=
ult counts=0A>>=0A>>=A0 =A0 =A0 =A0 =A0 scan=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 //.addFamily(xFamily)=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .=
addFamily(yFamily)=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .addFamily(zFami=
ly);=0A>> and=0A>>=A0 =A0 =A0 =A0 =A0 scan=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 .addFamily(xFamily)=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .addFam=
ily(yFamily)=0A>>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .addFamily(zFamily);=
=0A>>=0A>>=0A>> There is no error message, and I don't see anything in the =
Scan=0A>> documentation.=A0 Does anyone know what is going on?=0A>>=0A>> Th=
anks=0A>> Peter=0A>>=0A>>=0A>>=0A>
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