Structural Function Inlining Technique for Structurally Recursive XML Queries

Structurally recursive XML queries are an important query class that follows the structure of XML data. At present, it is difficult for XQuery to type and optimize structurally recursive queries because of polymorphic recursive functions involved in the queries. In this paper, we propose a new technique called structural function inlining which inlines recursive functions used in a query by making good use of available type information. Based on the technique, we develop a new approach to typing and optimizing structurally recursive queries. The new approach yields a more precise result type for a query. Furthermore, it produces an optimal algebraic expression for the query with respect to the type information. When a structurally recursive query is applied to non-recursive XML data, our approach translates the query into a finitely nested iterations. We conducted several experiments with commonly used real-life and synthetic datasets. The experimental results show that the number of ...

• Type: Journal
• Year: 2002
• Where: VLDB
• Authors: Chang-Won Park, Jun-Ki Min, Chin-Wan Chung
• Keywords: Database, Polymorphic Recursive Functions, Recursive Functions, Recursive Queries, VLDB 2002