Quick tutorial on doing project validation within GoodData. The function will tell you about any orphan records, referential integrity, missing values from reports, and general stuff that's screwed up within the LDM or data of the project.
1) go to https://secure.gooddata.com/gdc/md/<PID>
2) hit "validateproject"
3) Follow steps and links ... for a big project this may take a few minutes to run