Author: zjushch
Date: Wed Mar 27 03:08:12 2013
New Revision: 1461396
URL: http://svn.apache.org/r1461396
Log:
HBASE-8190 Add documentation of region merges to the book
Modified:
hbase/trunk/src/docbkx/book.xml
Modified: hbase/trunk/src/docbkx/book.xml
URL:
http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/book.xml?rev=1461396&r1=1461395&r2=1461396&view=diff
==============================================================================
--- hbase/trunk/src/docbkx/book.xml (original)
+++ hbase/trunk/src/docbkx/book.xml Wed Mar 27 03:08:12 2013
@@ -2175,6 +2175,28 @@ myHtd.setValue(HTableDescriptor.SPLIT_PO
</para>
</section>
</section>
+
+ <section>
+ <title>Online Region Merges</title>
+
+ <para>Both Master and Regionserver participate in the event of online
region merges.
+ Client sends merge RPC to master, then master moves the regions
together to the
+ same regionserver where the more heavily loaded region resided,
finally master
+ send merge request to this regionserver and regionserver run the
region merges.
+ Similar with process of region splits, region merges run as a local
transaction
+ on the regionserver, offlines the regions and then merges two regions
on the file
+ system, atomically delete merging regions from META and add merged
region to the META,
+ opens merged region on the regionserver and reports the merge to
Master at last.
+ </para>
+ <para>An example of region merges in the hbase shell
+ <programlisting>$ hbase> merge_region 'ENCODED_REGIONNAME',
'ENCODED_REGIONNAME'
+ hbase> merge_region 'ENCODED_REGIONNAME', 'ENCODED_REGIONNAME', true
+ </programlisting>
+ It's an asynchronous operation and call returns immediately without
waiting merge completed.
+ Passing 'true' as the optional third parameter will force a merge
('force' merges regardless
+ else merge will fail unless passed adjacent regions. 'force' is for
expert use only)
+ </para>
+ </section>
<section xml:id="store">
<title>Store</title>
