Cost-Based Path Indices Constructing for XML Documents
XU Zheng-chuan · Journal of Chinese Computer Systems · 2006
Path expressions pose a tough challenge for efficient XML query processing.Based on the new index structure for efficient evaluation of path expression queries — Structural Map which is invented by our lab,in order to reduce the space cost for constructing path indices,we present a cost model for the space consumption of indices and their benefit to XML queries processing.Given the workload of a target application,we adopt a greedy algorithm to select some map indices to construct,and get a near-optimal index schema(NOIS).When workload changes,system must automatically adjust its index schema for improving query-processing efficiency.The automatic index schema adaptation strategies are given.Our experimental study shows that query performance gets significant improvement over the case of without indices while consuming some extra disk space of modest size,and a near optimal tradeoff between the consumption of disk space and the efficiency of query evaluation is achieved.