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HBASE-4242 Add documentation for HBASE-4071 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1160988 13f79535-47bb-0310-9956-ffa450edef68
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Michael Stack 2011-08-24 06:54:38 +00:00
parent 48bdcd353b
commit ca64985a43
2 changed files with 16 additions and 0 deletions
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1
CHANGES.txt
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@ -456,6 +456,7 @@ Release 0.91.0 - Unreleased
(todd)
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

15
src/docbkx/book.xml
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@ -263,6 +263,21 @@ admin.enableTable(table);
compactions. The number of versions may need to be increased or decreased depending on application needs.
</para>
</section>
<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">
<title>
Immutability of Rowkeys