Java

One of the first questions that a 'traditional' ETL engineer asks when learning hadoop is, "How do I do a join ?"

For instance, how can we do in hadoop something like querying for the names of all employees who are in a California city:

SELECT e.name, c.name from employees e INNER JOIN cities c
    on e.city_id = c.id AND c.state ='CA'

Today's rich IDEs make a lot of tasks easier...usually. With Java and its IDEs you often end up spending more time than you anticipated to just set up a project, especially when dealing with the complexities of J2EE: there are multiple versions of the specifications 1.3,1.4,5.0), each one with multiple implementations by different vendors plus extensions (richfaces, struts, seam, spring..). You have also to choose the container (tomcat, glassfish, jboss...). Last but not least, you can also pick different building tools (abt, maven...).