A Framework for Intensional Query Optimization.
Parke Godfrey, Jarek Gryz · 1996
this paper. These costs can be non-trivial. However, efficient techniques for such---in particular, identifying the null unfoldings of a query---have been explored [10], and developed within the context of the Carmin project, a cooperative database system [7, 8, 11]. These techniques could be extended to identify when cached queries and materialized views can be used to evaluate certain unfoldings of queries. It is a difficult question how to identify candidate unfoldings for SQO or QF. This is a research question we are currently exploring. 7 Evaluating Discounted Queries