Towards set-oriented recursive XML query in pattern-based logic views

Recursive query is an interesting and subtle topic in XML query. Existing XML query languages often resort to recursive function or recursive predicate to present recursive XML query. However, this approach implicitly adopts a tuple-oriented way to query processing which is not fit for the set-oriented data processing in databases. In this paper, we propose a new approach to presenting recursive XML query in a pattern-based logic view named CDV. CDV deploys conjunctive and disjunctive operators to compose tree-like patterns, which can expressively specify the logic semantics in XML elements. With the assistance of the descendant operator, the syntactic and semantic mechanisms of CDV, the recursive XML query can be easily presented in a set-oriented way. We demonstrate the usage and advantage of the CDV in typical recursive queries.