Typechecking XML Views of Relational Databases

Noga Alon, Tova Milo, Frank Neven, Dan Suciu, Victor Vianu

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


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 article 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.

Original languageEnglish (US)
Pages (from-to)315-354
Number of pages40
JournalACM Transactions on Computational Logic
Issue number3
StatePublished - Jul 1 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • General Computer Science
  • Logic
  • Computational Mathematics


  • Algorithms
  • Complexity
  • Languages
  • Theory
  • XML
  • logic
  • relational databases
  • typechecking


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