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From ndimi...@apache.org
Subject [2/2] git commit: HBASE-11752 Document blockcache prefetch option (Misty Stanley-Jones)
Date Wed, 20 Aug 2014 19:58:15 GMT
HBASE-11752 Document blockcache prefetch option (Misty Stanley-Jones)


Project: http://git-wip-us.apache.org/repos/asf/hbase/repo
Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/7d48fa69
Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/7d48fa69
Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/7d48fa69

Branch: refs/heads/branch-1
Commit: 7d48fa698bccfa18d3ae9b27f2b2809eaddd854b
Parents: 8670fb3
Author: Nick Dimiduk <ndimiduk@apache.org>
Authored: Wed Aug 20 12:56:43 2014 -0700
Committer: Nick Dimiduk <ndimiduk@apache.org>
Committed: Wed Aug 20 12:57:20 2014 -0700

----------------------------------------------------------------------
 src/main/docbkx/book.xml        | 14 ++++++++------
 src/main/docbkx/performance.xml | 31 +++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 6 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/hbase/blob/7d48fa69/src/main/docbkx/book.xml
----------------------------------------------------------------------
diff --git a/src/main/docbkx/book.xml b/src/main/docbkx/book.xml
index 163bea3..675564d 100644
--- a/src/main/docbkx/book.xml
+++ b/src/main/docbkx/book.xml
@@ -2134,12 +2134,14 @@ rs.close();
         </section>
         <section xml:id="cache.configurations">
             <title>General Cache Configurations</title>
-            <para>Apart from the cache implementaiton itself, you can set some general
-                configuration options to control how the cache performs.
-               See <link
-                xlink:href="http://hbase.apache.org/devapidocs/org/apache/hadoop/hbase/io/hfile/CacheConfig.html"
/>.
-              After setting any of these options, restart or rolling restart your cluster
for the
-              configuration to take effect. Check logs for errors or unexpected behavior.</para>
+          <para>Apart from the cache implementation itself, you can set some general
configuration
+            options to control how the cache performs. See <link
+              xlink:href="http://hbase.apache.org/devapidocs/org/apache/hadoop/hbase/io/hfile/CacheConfig.html"
+            />. After setting any of these options, restart or rolling restart your cluster
for the
+            configuration to take effect. Check logs for errors or unexpected behavior.</para>
+          <para>See also <xref linkend="blockcache.prefetch"/>, which discusses
a new option
+            introduced in <link xlink:href="https://issues.apache.org/jira/browse/HBASE-9857"
+              >HBASE-9857</link>.</para>
       </section>
         <section
           xml:id="block.cache.design">

http://git-wip-us.apache.org/repos/asf/hbase/blob/7d48fa69/src/main/docbkx/performance.xml
----------------------------------------------------------------------
diff --git a/src/main/docbkx/performance.xml b/src/main/docbkx/performance.xml
index 58557db..599677c 100644
--- a/src/main/docbkx/performance.xml
+++ b/src/main/docbkx/performance.xml
@@ -217,6 +217,37 @@
         A memory setting for the RegionServer process.
         </para>
     </section>
+    <section xml:id="blockcache.prefetch">
+      <title>Prefetch Option for Blockcache</title>
+      <para><link xlink:href="https://issues.apache.org/jira/browse/HBASE-9857">HBASE-9857</link>
+        adds a new option to prefetch HFile contents when opening the blockcache, if a columnfamily
+        or regionserver property is set. This option is available for HBase 0.98.3 and later.
The
+        purpose is to warm the blockcache as rapidly as possible after the cache is opened,
using
+        in-memory table data, and not counting the prefetching as cache misses. This is great
for
+        fast reads, but is not a good idea if the data to be preloaded will not fit into
the
+        blockcache. It is useful for tuning the IO impact of prefetching versus the time
before all
+        data blocks are in cache. </para>
+      <para>To enable prefetching on a given column family, you can use HBase Shell
or use the
+        API.</para>
+      <example>
+        <title>Enable Prefetch Using HBase Shell</title>
+        <screen>hbase> create 'MyTable', { NAME => 'myCF', PREFETCH_BLOCKS_ON_OPEN
=> 'true' }</screen>
+      </example>
+      <example>
+        <title>Enable Prefetch Using the API</title>
+        <programlisting language="java">
+// ...
+HTableDescriptor tableDesc = new HTableDescriptor("myTable");
+HColumnDescriptor cfDesc = new HColumnDescriptor("myCF");
+cfDesc.setPrefetchBlocksOnOpen(true);
+tableDesc.addFamily(cfDesc);
+// ...        
+        </programlisting>
+      </example>
+      <para>See the API documentation for <link
+          xlink:href="https://hbase.apache.org/apidocs/org/apache/hadoop/hbase/io/hfile/CacheConfig.html"
+          >CacheConfig</link>.</para>
+    </section>
     <section xml:id="perf.rs.memstore.size">
         <title><varname>hbase.regionserver.global.memstore.size</varname></title>
         <para>See <xref linkend="hbase.regionserver.global.memstore.size"/>.


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