3

Describing Data Sources

In order for a data integration system to process a query over a set of data sources, the system must know which sources are available, what data exist in each source, and how each source can be accessed. The source descriptions in a data integration system encode this information. In this chapter we study the different components of source descriptions and identify the trade-offs involved in designing formalisms for source descriptions.

To put the topic of this chapter in context, consider the architecture of a data integration system, redrawn in Figure 3.1. Recall that a user (or an application) poses a query to the data integration system using the relations and attributes of the mediated schema. The system then reformulates ...

Get Principles of Data Integration now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.