Constraint-driven join processing in a Web Warehouse

摘要

There has been considerable research in join operation in relational databases. In this paper, we introduce the concept of web join for combining hyperlinked Web data. Web join is one of the web algebraic operator in our web warehousing system called Whoweda (WareHouse Of WEb DAta). Similar to its relational counterpart, it can be used to gather useful, composite information from two web tables. The significance of web join perhaps can be best realized when we wish to combine data from a Web site where some of the information in the Web site is no longer available due to changes to the site. A web join operation can be constraint-free or constraint-driven depending on the absence or presence of join conditions. In this paper, we focus our discussion on constraint-driven web join operation, i.e., web join operation in the presence of user-specified join conditions. Specifically, we discuss the syntax, semantics and algorithm of web join operator.