Optimal schema hierarchies in searching semistructured databases by conjunctive regular path queries

An approach to estimating effectiveness of index usage when searching semistructured databases consisting of OEM documents is presented. In addition to the estimation of the hierarchy optimality from the standpoint of calculation of conjunctive regular path queries, this approach allows one to take into account arbitrary distributions of query probabilities. Algorithms for index construction are given, and estimates of their complexity are obtained. These estimates clearly demonstrate efficiency of the approach and practical applicability of the algorithms suggested.