A Framework for the Relational Implementation of Tree Algebra to Retrieve Structured Document Fragments

摘要

Naive users typically query documents with keywords. The problem of retrieval unit when keyword queries are posed against a structured document consisting of several logical components has been studied in the past. We developed a new query model based on tree algebra, which successfully resolves this problem. However, one important issue any such effective theoretical model has to deal with, is the difficulty in its equally effective implementation. In this paper, we overview our query model and explore how this model can be successfully implemented using an existing relational database technology. Tree nodes representing logical components of a structured document are indexed with their pre-order and post-order rankings and stored as a relation. We then show how the basic algebraic operation defined in our query model can be transformed into a simple SQL query against this relation. We also discuss various issues regarding query optimization on the implementation level of the model.