HBASE-5069 [book] Document how to count rows

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1415733 13f79535-47bb-0310-9956-ffa450edef68

src/docbkx/ops_mgt.xml

@@ -266,8 +266,10 @@ row10	c1	c2
     </section>
     <section xml:id="rowcounter">
        <title>RowCounter</title>
-       <para>RowCounter is a utility that will count all the rows of a table.  This is a good utility to use
+       <para>RowCounter is a mapreduce job to count all the rows of a table.  This is a good utility to use
            as a sanity check to ensure that HBase can read all the blocks of a table if there are any concerns of metadata inconsistency.
+           It will run the mapreduce all in a single process but it will run faster if you have a MapReduce cluster in place for it to
+           exploit.
 <programlisting>$ bin/hbase org.apache.hadoop.hbase.mapreduce.RowCounter &lt;tablename&gt; [&lt;column1&gt; &lt;column2&gt;...]
 </programlisting>
        </para>

src/docbkx/shell.xml

@@ -104,5 +104,16 @@
                </para>
             </section>
          </section>
+        <section><title>Commands</title>
+            <section><title>count</title>
+                <para>Count command returns the number of rows in a table.
+		    It's quite fast when configured with the right CACHE
+            <programlisting>hbase> count '&lt;tablename&gt;', CACHE => 1000</programlisting>
+            The above count fetches 1000 rows at a time.  Set CACHE lower if your rows are big.
+            Default is to fetch one row at a time.
+                 </para>
+            </section>
+         </section>
+
     </section>
   </chapter>