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From dm...@apache.org
Subject svn commit: r1196801 - /hbase/trunk/src/docbkx/book.xml
Date Wed, 02 Nov 2011 21:09:47 GMT
Author: dmeil
Date: Wed Nov  2 21:09:47 2011
New Revision: 1196801

URL: http://svn.apache.org/viewvc?rev=1196801&view=rev
HBASE-4731 book.xml, schema design - rowkey numeric example


Modified: hbase/trunk/src/docbkx/book.xml
URL: http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/book.xml?rev=1196801&r1=1196800&r2=1196801&view=diff
--- hbase/trunk/src/docbkx/book.xml (original)
+++ hbase/trunk/src/docbkx/book.xml Wed Nov  2 21:09:47 2011
@@ -614,7 +614,8 @@ admin.enableTable(table);               
        <para>Most of the time small inefficiencies don't matter all that much.  Unfortunately,
          this is a case where they do.  Whatever patterns are selected for ColumnFamilies,
attributes, and rowkeys they could be repeated
-       several billion times in your data.  See <xref linkend="keyvalue"/> for more
information on HBase stores data internally.</para>
+       several billion times in your data. </para>
+       <para>See <xref linkend="keyvalue"/> for more information on HBase stores
data internally.</para>
        <section xml:id="keysize.cf"><title>Column Families</title>
          <para>Try to keep the ColumnFamily names as small as possible, preferably
one character (e.g. "d" for data/default).
@@ -630,6 +631,13 @@ admin.enableTable(table);               
          when designing rowkeys.
+       <section xml:id="keysize.example"><title>Numeric Example</title>
+         <para>A long is 8 bytes.  You can store an unsigned number up to 18,446,744,073,709,551,615
in those eight bytes.
+            If you stored this number as a String -- presuming a byte per character -- you
need nearly 3x the bytes.
+            This is a perfect example of a small inefficiency that may not seem like much,
but can add up in HBase when 
+            used as rowkeys.
+         </para>
+       </section>
     <section xml:id="reverse.timestamp"><title>Reverse Timestamps</title>
     <para>A common problem in database processing is quickly finding the most recent
version of a value.  A technique using reverse timestamps

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