For most cases, the only prerequisite is that you must have properly configured the connection from this Job to the Hadoop distribution where the data of interest is stored.
To view the source data, right-click the input component, for example, tHDFSInput, you are using in the workspace and from the contextual menu, select Data viewer.
To view the output data after an execution, right-click the output component, for example, tHDFSOutput, you are using in the workspace and from the contextual menu, select Data viewer.
The following image is the example of the Data viewer with data read from a remote Hadoop server. The schema of the data is defined in the component from which the Data Viewer is called.
Viewing data from a MapR cluster
If you are using a MapR distribution, that is to say, you have to install its MapR client in the machine where the Studio is, you need to set the -Djava.library.path argument for the Studio to access the native library of that MapR client.
From the menu bar of the Studio, click Preferences dialog box.to open the
Expand Talend and select Run/Debug.
In the Job Run VM arguments area, click New to display the Set the VM Argument dialog box.
Set the -Djava.library.path argument, for example, enter -Djava.library.path=C:\opt\mapr\lib\native\Windows_7, if you are using Windows 7, or enter -Djava.library.path=/opt/mapr/lib if you are using Linux.
Click OK to close this dialog box and this argument is added to the Argument table.
Click Apply to validate these changes and click OK to close the Preferences dialog box.