Query Reformulation With Constraints
ACM SIGMOD Record(2006)
摘要
Let Σ 1 , Σ 2 be two schemas, which may overlap, C be a set of constraints on the joint schema Σ 1 ∪ Σ 2 , and q 1 be a Σ 1 -query. An (equivalent) reformulation of q 1 in the presence of C is a Σ 2 -query, q 2 , such that q 2 gives the same answers as q 1 on any Σ 1 ∪ Σ 2 -database instance that satisfies C . In general, there may exist multiple such reformulations and choosing among them may require, for example, a cost model.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络