Remembering the Future

Furthermore you've the possibility to open the WinFS database in SQL-Server: the database-file lives in the folder c:\windows\system32\winfs\data\catalog.mdf.
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When you then look to the extracted mapping file and the database you can see that each <type>-element is mapped to a database table - cool isn't it? From the default namespace of the mapping file (http://www.microsoft.com/ObjectSpaces-v1) you can see that MS is using a version of object spaces for creating the mapping between the CLR types and the database tables.

In WinFS we have an item table and a relationship table. The item table has an ItemId column. The relationship table has SourceItemId and TargetItemId columns. At the SQL level, when querying for related items you join through the relationship table.