I’ve built a couple of custom reports for a client, and in doing so I’ve been forced to dive deep into the TFS 2010 database, which sometimes leads to interesting findings.

This time I found a strange approach to Areas and Iterations. For all work items areas and iterations are stored in the table xxTree. But then there are two other tables named tbl_Areas and tbl_Iterations, and they also contain all areas and iterations. But without all the other stuff found in xxTree. Now, one might be tempted to believe that these tables are somehow connected and perhaps contain a foreign key pointing to the  xxTree table. But no… As far as I can tell, xxTree is for work items while tbl_Areas and tbl_Iterations is used by MTM2010 for mapping test plans to areas and iterations.

So for anyone  writing queries using these tables, make sure you use the right ones or you will end up with some very strange results.