Database Reference
In-Depth Information
Executing, debugging, monitoring, and looking at
results
To execute this example, compile the code and create a JAR file. Add any required external
libraries or dependency to the classpath or edit
conf/hadoop-env.sh
and add the loc-
ation of the JARs. One of the hard requirements to get all this Cassandra-related stuff run-
ning is to have the Cassandra's
lib
directory in Hadoop's classpath. To do that, edit
$HADOOP_HOME/conf/hadoop-env.sh
and update the classpath like this:
$ conf/hadoop-env.sh
# Extra Java CLASSPATH elements.Optional.
# export HADOOP_CLASSPATH=
export HADOOP_CLASSPATH=/home/nishant/apps/cassandra11/lib/
*:$HADOOP_CLASSPATH
Make sure Hadoop and Cassandra are completely up and running. To execute your MapRe-
duce program, submit the JAR file to Hadoop with an appropriate classpath, if needed, and
a fully qualified class name of the main class, as follows:
$ bin/hadoop jar masteringcassandra-0.0.1-SNAPSHOT.jar \
The following screenshot shows Hadoop JobTracker GUI. It enables users to watch run-
ning jobs and completed jobs; most importantly, you can see logs, system outs, and system
error streams by drilling into the job IDs:
Hadoop provides a pretty simple web-based GUI to monitor and view debug logs, system
out stream messages, and system error stream messages. One can monitor the status of a
running, failed, or previously run job in detail. By default, this portal is available at
ht-
