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From st...@apache.org
Subject svn commit: r1160988 - in /hbase/trunk: CHANGES.txt src/docbkx/book.xml
Date Wed, 24 Aug 2011 06:54:38 GMT
Author: stack
Date: Wed Aug 24 06:54:38 2011
New Revision: 1160988

URL: http://svn.apache.org/viewvc?rev=1160988&view=rev
HBASE-4242 Add documentation for HBASE-4071


Modified: hbase/trunk/CHANGES.txt
URL: http://svn.apache.org/viewvc/hbase/trunk/CHANGES.txt?rev=1160988&r1=1160987&r2=1160988&view=diff
--- hbase/trunk/CHANGES.txt (original)
+++ hbase/trunk/CHANGES.txt Wed Aug 24 06:54:38 2011
@@ -456,6 +456,7 @@ Release 0.91.0 - Unreleased
    HBASE-4071  Data GC: Remove all versions > TTL EXCEPT the last
                written version (Lars Hofhansl)
+   HBASE-4242  Add documentation for HBASE-4071 (Lars Hofhansl)
 Release 0.90.5 - Unreleased

Modified: hbase/trunk/src/docbkx/book.xml
URL: http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/book.xml?rev=1160988&r1=1160987&r2=1160988&view=diff
--- hbase/trunk/src/docbkx/book.xml (original)
+++ hbase/trunk/src/docbkx/book.xml Wed Aug 24 06:54:38 2011
@@ -263,6 +263,21 @@ admin.enableTable(table);               
       compactions.  The number of versions may need to be increased or decreased depending
on application needs.
+  <section xml:id="schema.minversions">
+  <title>
+  Minimum Number of Versions
+  </title>
+  <para>Like number of row versions, the minimum number of row versions to keep is
configured per column
+      family via <link xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/HColumnDescriptor.html">HColumnDescriptor</link>.
+      The default is 0, which means the feature is disabled.
+      The minimum number of row versions parameter is used together with the time-to-live
parameter and can be combined with the
+      number of row versions parameter to allow configurations such as
+      "keep the last T minutes worth of data, at most N versions, <emphasis>but keep
at least M versions around</emphasis>"
+      (where M is the value for minimum number of row versions, M&lt;=N).
+      This parameter should only be set when time-to-live is enabled for a column family
and must be less or equal to the 
+      number of row versions.
+  </para>
+  </section>
   <section xml:id="changing.rowkeys">
   Immutability of Rowkeys

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