QTwig: A structural join algorithm for efficient query retrieval based on region-based labeling

Dependability on XML has increased tremendously over the years. As such the need for efficient query processing technique is certainly important. Despite the fact that these techniques are able to process queries with various edge combinations, they still suffer from processing overheads by buffering large amount of intermediate results particularly for parent-child (P-C) edges. Therefore, in this paper, we propose architecture named ReLaQ, which comprises of two components, ReLab+ (node annotator) and QTwig (query processor) for efficient XML query processing. QTwig improves retrieval time by incorporating a pruning technique that avoids accessing irrelevant data during query processing. Experimental results indicated that ReLaQ superseded TwigStack for both path and twig queries using both regular-and skewed-structured datasets. In addition, this is also proven by means of correctness analysis of ReLaQ.