This paper presents the rudiments of a theory of schema design for databases containing high dimensional features of the type used for describing multimedia data. We introduce a model of multimedia database based on tables containing feature types, and the concept of schema design, which is based on splitting tables depending on the functional relations between different parts of the features. We show that certain relations between substructures of a same feature structure can lead to schemas for which efficient algorithms for -nearest neighbor and range searches can be defined.