First Class Meta-Data Supporting Exploratory Analysis

If overview, zoom, filter, and details are sufficiently important to make them the mantra of Information Visualization [Shneiderman 1996], why aren't they first class objects in InfoVis systems? Why not specify what the overview is of, perform set operations on filters, and annotate details with usage information? While these have all been implemented as one-off features, this paper outlines techniques for persistent storage of session metadata, so that they emerge from the data architecture. The techniques rely on relational databases for their expressiveness and object-oriented database concepts for their direct correspondence to screen objects and operations. They supports arbitrary specification of active datasets, set operations, derived attributes, hierarchical attributes, and reification. Much of the paper describes technical details, such as SQL and database indexes, necessary to build an efficient expressive elegant semantic superstructure. CR Categories: H.3.7 [Information Storage and Retrieval]: Digital Libraries---User issues. General Terms: Algorithms, Human Factors.