[Hadoop Wiki] Trivial Update of "Hbase/MapReduce" by stack

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The following page has been changed by stack:
http://wiki.apache.org/hadoop/Hbase/MapReduce

The comment on the change is:
Update to suit new state of affairs: i.e. hbase its own project.

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  = Hbase, MapReduce and the CLASSPATH =
  
- An hbase cluster configuration is made up of an aggregation of the hbase particulars found at ''$HBASE_CONF_DIR'' -- default location is ''$HBASE_HOME/conf'' -- and the hadoop configuration in ''$HADOOP_CONF_DIR'', usually ''$HADOOP_HOME/conf''.  When hbase start/stop scripts run, they will read ''$HBASE_CONF_DIR'' content and then that of ''$HADOOP_CONF_DIR''.
+ !MapReduce jobs deployed to a mapreduce cluster do not usually have access to the configuration under ''$HBASE_CONF_DIR'' nor to hbase classes.
  
- !MapReduce job jars deployed to a mapreduce cluster do not usually have access to ''$HBASE_CONF_DIR''.  Any hbase particular configuration not hard-coded into the job jar classes -- e.g. the address of the target hbase master -- needs to be either included explicitly in the job jar, by jarring an ''hbase-site.xml'' into a conf subdirectory, or adding a hbase-site.xml under ''$HADOOP_HOME/conf'' and copying it across the mapreduce cluster.
+ Any hbase particular configuration not hard-coded into the job jar classes -- e.g. the address of the target hbase master -- that is needed by running maps and/or reduces needs to be either included explicitly in the job jar, by jarring an appropriately configured ''hbase-site.xml'' into a conf subdirectory, or by adding an ''hbase-site.xml'' under ''$HADOOP_HOME/conf'' and copying it across the mapreduce cluster.  The same holds true for any hbase classes referenced by the mapreduce job jar.  By default the hbase classes are not available on the general mapreduce ''CLASSPATH''.  To add them, you have a couple of options. Either include the hadoop-X.X.X-hbase.jar in the job jar under the lib subdirectory or copy the hadoop-X.X.X-hbase.jar to $HADOOP_HOME/lib and copy it across the cluster.
  
- The same holds true for any hbase classes referenced by the mapreduce job jar.  By default the hbase classes are not available on the general mapreduce ''CLASSPATH''.  To add them, you have a couple of options. Either include the hadoop-X.X.X-hbase.jar in the job jar under the lib subdirectory or copy the hadoop-X.X.X-hbase.jar to $HADOOP_HOME/lib and copy it across the cluster.  But the cleanest means of adding hbase to the cluster CLASSPATH is by uncommenting ''HADOOP_CLASSPATH'' in ''$HADOOP_HOME/conf/hadoop-env.sh'' adding the path to the hbase jar, usually ''$HADOOP_HOME/contrib/hbase/hadoop-X.X.X-hbase.jar'', and then copying the amended configuration across the cluster.  You'll need to restart the mapreduce cluster if you want it to notice the new configuration.
+ But the cleanest means of adding hbase configuration and classes to the cluster CLASSPATH is by uncommenting ''HADOOP_CLASSPATH'' in ''$HADOOP_HOME/conf/hadoop-env.sh'' and adding the path to the hbase jar and ''conf'' directory.  Then copy the amended configuration across the cluster.  You'll need to restart the mapreduce cluster if you want it to notice the new configuration.
  
  For example, here is how you would amend ''hadoop-env.sh'' adding hbase classes and the !PerformanceEvaluation class from hbase test classes to the hadoop ''CLASSPATH'':
  
  {{{# Extra Java CLASSPATH elements.  Optional.
  # export HADOOP_CLASSPATH=
- export HADOOP_CLASSPATH=/home/user/hadoop-trunk/build/contrib/hbase/test:/home/user/hadoop-trunk/build/contrib/hbase/hadoop-0.15.0-dev-hbase.jar}}}
+ export HADOOP_CLASSPATH=$HBASE_HOME/build/test:$HBASE_HOME/build/hadoop-0.15.0-dev-hbase.jar}}}
  
+ (Expand $HBASE_HOME appropriately in the in accordance with your local environment)
+ 
+ And then, this is how you would run the PerformanceEvaluation MR job to put up 4 clients:
+ 
+ {{{ > $HADOOP_HOME/bin/hadoop org.apache.hadoop.hbase.PerformanceEvaluation sequentialWrite 4 }}}
+ 
+ (The PerformanceEvaluation class wil be found on the CLASSPATH because you added $HBASE_HOME/build/test to HADOOP_CLASSPATH)
  
  = Hbase as MapReduce job data source and sink =