Database support for evolving data in product design

We argue that database support for design processes is still inadequate, despite the many transaction models that have been put forth to fill this deficiency. In our opinion, substantial improvement is not to be had by introducing yet another transaction model, but by questioning the basic paradigm of transaction processing itself: Instead of the usual view of transactions as destructive operations replacing an outdated database state with a more current one, we propose to view design transactions as non-destructive operations importing additional knowledge about an essentially unchanging final design solution. This leads to a model of designing with constraints, and a natural way of concurrent design. We give a formal presentation of the model and then discuss implementation techniques for centralized and distributed constraint management