(This is different but related to where a database is designed as a "one size fits all" which doesn't cover attribute volatility).
This assumption, almost unrealistic in the context of traditional information systems, becomes unacceptable in the context of systems that retain large volumes of historical information or those such as web information systems, that due to the distributed and cooperative nature of their development, are subject of an even stronger pressure toward change (from 39% to over 500% more intense than in traditional settings).
[2] Due to this historical heritage the process of schema evolution as of 2008 a particularly taxing one.
It is, in fact, widely acknowledged that the data management core of an applications is one of the most difficult and critical components to evolve.
The key problem is the impact of the schema evolution on queries and applications.