Compiling Source Descriptions for Efficient and Flexible Information Integration

摘要

Integrating data from heterogeneous data sources is a critical problem that has received a great deal of attention in recent years. There are two competing approaches to address this problem. The traditional approach, which first appeared in Multibase and more recently in HERMES and TSIMMIS, often called global-as-view, defines the global model as a view on the sources. A more recent approach, sometimes referred to as local-as-view or view rewriting, defines the sources as views on the global model. The disadvantage of the first approach is that a person must re-engineer the definitions of the global model whenever any of the sources change or when new sources are added. The view rewriting approach does not suffer from this drawback, but the problem of rewriting queries into equivalent plans using views is computationally hard and must be performed for each query at run-time.