Logic in Computer Science, Symposium on (2001)
June 16, 2001 to June 19, 2001
Noga Alon , Tel Aviv University
Tova Milo , Tel Aviv University
Frank Neven , Limburgs Universitair Centrum
Dan Suciu , University of Washington
Victor Vianu , U.C. San Diego
Abstract: Motivated by the need to export relational databases as XML data in the context of the Web, we investigate the typechecking problem for transformations of relational data into tree data (XML).The problem consists of statically verifying that the output of every transformation belongs to a given output tree language (specified for XML by a DTD), for input databases satisfying given integrity constraints. The typechecking problem is parameterized by the class of formulas defining the transformation, the class of output tree languages, and the class of integrity constraints. While undecidable in its most general formulation, the typechecking problem has many special cases of practical interest that turn out to be decidable. The main contribution of this paper is to trace a fairly tight boundary of decidability for typechecking in this framework. In the decidable cases we examine the complexity, and show lower and upper bounds. We also exhibit a practically appealing restriction for which typechecking is in PTIME.
V. Vianu, T. Milo, D. Suciu, N. Alon and F. Neven, "Typechecking XML Views of Relational Databases," Logic in Computer Science, Symposium on(LICS), Boston, Massachusetts, 2001, pp. 0421.