Peter Williams: connascence == legacy
very interesting post from Peter Williams on the effect tight coupling between databases and components (Connascence) can have on your application. this quote does a pretty good job of making the point.
The forms and degree of connascence that such an approach necessitate make it recipe for disaster. Such high level of connascence will raise the costs of change (read: improvment) in all the modules involved. Application systems tend to get more integrated over time so the cost of improvement rises rapidly in systems that use integration databases. After a while the cost of change will become so high that only improvements that provide huge value to the business will be worth the cost. For weak, undisciplined teams this will happen very rapidly. For strong, smart and highly disciplined teams it will take a bit longer, but it will happen. Once you allow more than one module to access your app’s database forever will it dominate your destiny.