hbase-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From mi...@apache.org
Subject git commit: HBASE-11784 Document global configuration for maxVersion
Date Tue, 16 Sep 2014 03:04:46 GMT
Repository: hbase
Updated Branches:
  refs/heads/branch-1 1f1a2c514 -> d93b5ce04


HBASE-11784 Document global configuration for maxVersion


Project: http://git-wip-us.apache.org/repos/asf/hbase/repo
Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/d93b5ce0
Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/d93b5ce0
Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/d93b5ce0

Branch: refs/heads/branch-1
Commit: d93b5ce04f245bb482b4b911fa3554adf39bd852
Parents: 1f1a2c5
Author: Misty Stanley-Jones <mstanleyjones@cloudera.com>
Authored: Tue Sep 16 13:04:28 2014 +1000
Committer: Misty Stanley-Jones <mstanleyjones@cloudera.com>
Committed: Tue Sep 16 13:04:28 2014 +1000

----------------------------------------------------------------------
 src/main/docbkx/book.xml          | 31 +++++++++++++++++++++++++++++++
 src/main/docbkx/schema_design.xml | 11 ++++++++---
 2 files changed, 39 insertions(+), 3 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/hbase/blob/d93b5ce0/src/main/docbkx/book.xml
----------------------------------------------------------------------
diff --git a/src/main/docbkx/book.xml b/src/main/docbkx/book.xml
index b8247b9..50aa0d9 100644
--- a/src/main/docbkx/book.xml
+++ b/src/main/docbkx/book.xml
@@ -652,6 +652,37 @@ try {
               <emphasis>Overwriting values at existing timestamps</emphasis>
mentioned in the
             article no longer holds in HBase. This section is basically a synopsis of this
article
             by Bruno Dumon.</para>
+      
+      <section xml:id="specify.number.of.versions">
+        <title>Specifying the Number of Versions to Store</title>
+        <para>The maximum number of versions to store for a given column is part of
the column
+          schema and is specified at table creation, or via an <command>alter</command>
command, via
+            <code>HColumnDescriptor.DEFAULT_VERSIONS</code>. Prior to HBase 0.96,
the default number
+          of versions kept was <literal>3</literal>, but in 0.96 and newer has
been changed to
+            <literal>1</literal>.</para>
+        <example>
+          <title>Modify the Maximum Number of Versions for a Column</title>
+          <para>This example uses HBase Shell to keep a maximum of 5 versions of column
+              <code>f1</code>. You could also use <link
+              xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/HColumnDescriptor.html"
+              >HColumnDescriptor</link>.</para>
+          <screen><![CDATA[hbase> alter ‘t1′, NAME => ‘f1′, VERSIONS
=> 5]]></screen>
+        </example>
+        <example>
+          <title>Modify the Minimum Number of Versions for a Column</title>
+          <para>You can also specify the minimum number of versions to store. By default,
this is
+            set to 0, which means the feature is disabled. The following example sets the
minimum
+            number of versions on field <code>f1</code> to <literal>2</literal>,
via HBase Shell.
+            You could also use <link
+              xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/HColumnDescriptor.html"
+              >HColumnDescriptor</link>.</para>
+          <screen><![CDATA[hbase> alter ‘t1′, NAME => ‘f1′, MIN_VERSIONS
=> 2]]></screen>
+        </example>
+        <para>Starting with HBase 0.98.2, you can specify a global default for the
maximum number of
+          versions kept for all newly-created columns, by setting
+            <option>hbase.column.max.version</option> in <filename>hbase-site.xml</filename>.
See
+            <xref linkend="hbase.column.max.version"/>.</para>
+      </section>
 
       <section
         xml:id="versions.ops">

http://git-wip-us.apache.org/repos/asf/hbase/blob/d93b5ce0/src/main/docbkx/schema_design.xml
----------------------------------------------------------------------
diff --git a/src/main/docbkx/schema_design.xml b/src/main/docbkx/schema_design.xml
index e4d3baa..9f3f350 100644
--- a/src/main/docbkx/schema_design.xml
+++ b/src/main/docbkx/schema_design.xml
@@ -439,15 +439,18 @@ public static byte[][] getHexSplits(String startKey, String endKey,
int numRegio
       xml:id="schema.versions.max">
       <title>Maximum Number of Versions</title>
       <para>The maximum number of row versions to store is configured per column family
via <link
-          xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/HColumnDescriptor.html">HColumnDescriptor</link>.
-        The default for max versions is 1. This is an important parameter because as described
in <xref
-          linkend="datamodel" /> section HBase does <emphasis>not</emphasis>
overwrite row values,
+          xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/HColumnDescriptor.html"
+          >HColumnDescriptor</link>. The default for max versions is 3 prior to
HBase 0.96.x, and 1
+        in newer versions. This is an important parameter because as described in <xref
+          linkend="datamodel"/> section HBase does <emphasis>not</emphasis>
overwrite row values,
         but rather stores different values per row by time (and qualifier). Excess versions
are
         removed during major compactions. The number of max versions may need to be increased
or
         decreased depending on application needs. </para>
       <para>It is not recommended setting the number of max versions to an exceedingly
high level
         (e.g., hundreds or more) unless those old values are very dear to you because this
will
         greatly increase StoreFile size. </para>
+      <para>See <xref linkend="specify.number.of.versions"/> for examples for
setting the maximum
+        number of versions on a given column or globally.</para>
     </section>
     <section
       xml:id="schema.minversions">
@@ -462,6 +465,8 @@ public static byte[][] getHexSplits(String startKey, String endKey, int
numRegio
           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 than the number of row versions. </para>
+      <para>See <xref linkend="specify.number.of.versions"/> for examples for
setting the minimum
+        number of versions on a given column.</para>
     </section>
   </section>
   <section


Mime
View raw message