An Adaptive Index of XML for Frequent Branching Path Queries

Structural index, which acts as a structural summary, plays an important role in query optimization over XML and semi-structured data. To speed up branching path queries, we introduce the notion of k-l-bisimilarity into M(k)-index and propose an adaptive structural index, MBF(k, l)-index, which supports branching paths with any complexity efficiently and inherits the advantage of avoiding over-refinement from M(k)-index. Our experiments have shown that the index performs more efficiently in terms of space consumption and query performance for branching or simple paths in comparison with the same kind of indexes.