Slide 5 of 52
Notes:
The burden of tables: labouring under an inappropriate storage mechanism and inappropriate concepts.
However, all leading RDBMSs are now 'universal servers' and some have user-pluggable and configurable indexes as well as ADTs (abstract data types - ideally user-definable too). For a company starting to develop a new Temporal GIS next year, for sale in 3-5 years, the choice of underlying DB depends more on marketing than technology: Informix is most open, but will it survive? Oracle has greatest penetration, but does not yet provide all the useful facilities.
What is clear is that the existing OO GIS have an enormous implementation advantage. But those companies may not want to invest in a Temporal GIS market which does not yet exist, and whose most likely user-bases (environmental monitoring, cadastre) are currently furthest away from the current OO GIS users (utilities and very large national mapping agencies).
Most non-spatial temporal-db research has concentrated on RDBMS and SQL, which is thus intensely and unnecessarily complicated.
The innate OO advantages will be demonstrated during the remainder of the seminar as we discuss detailed representations, indexes and relationships.
