MyLifeBits has at its heart a SQL Server database that can store content and metadata for a variety of
types, including contacts, documents, email, events, photos, songs, and video. Figure 2 illustrates the
MyLifeBits schema. All captured entities that are exposed to the user are called “Items.” Each item has
about 20 common attributes, registered in the _Items table. Items are of one or more types: the _Item-
ItemSubtype table indicates the specific the type(s) of each item. _ItemSubTypes enumerates the valid
types. For each item type (such as email message or image) there is an additional table for type-specific...