an introductory working example of hadoop we'll end this with small application in big data context for this we'll use hortonworks sandbox image this is virtual machine created by hortonworks to try some big data applications on local machine later on in this book you'll see how juju eases the installation of hadoop on multiple machines we'll use small data set of job salary data to run our first samplebut querying large data set of billions of rows would be equally easy the query language will seem like sqlbut behind the scenes mapreduce job will run and produce straightforward table of resultswhich can then be turned into bar graph the end result of this exercise looks like figure figure the end resultthe average salary by job description to get up and running as fast as possible we use hortonworks sandbox inside virtualbox virtualbox is virtualization tool that allows you to run another operating system inside your own operating system in this case you can run centos with an existing hadoop installation inside your installed operating system few steps are required to get the sandbox up and running on virtualbox cautionthe following steps were applicable at the time this was written (february ) download the virtual image from start your virtual machine host virtualbox can be downloaded from