If you are in a situation where the community person you are working with just is not suited for the task that they have taken on, stop!

It is not our intent to mentor people through their first Java program nor explain the complexities of OLAP. You can politely tell the community member to back up and either document requirements for the task so another (more capable) community or team member will have detailed specs when they pick up the project, or contribute documentation on currently implemented features. If you have to ask a community member to abandon an effort, please do so with a redirect to something else they can help with.