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Incremental XPath Evaluation
"... We study the problem of incrementally maintaining the result of an XPath query on an XML database under updates. In its most general form, this problem asks to maintain a materialized XPath view over an XML database. It assumes an underlying XML database D and a query Q. One is given a sequence of u ..."
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We study the problem of incrementally maintaining the result of an XPath query on an XML database under updates. In its most general form, this problem asks to maintain a materialized XPath view over an XML database. It assumes an underlying XML database D and a query Q. One is given a sequence of updates U to D and the problem is to compute the result of Q(U(D)), i.e., the result of evaluating query Q on the database D after having applied the updates U. In order to quickly answer this question, we are allowed to maintain an auxiliary data structure, and the complexity of the maintenance algorithms is measured in (i) the size of the auxiliary data structure, (ii) the worstcase time per update needed to compute Q(U(D)) and (iii) the worstcase time per update needed to bring the auxiliary data structure up to date. We allow three kinds of updates: node insertion, node deletion, and node relabeling. Our main results are that downward XPath queries can be incrementally maintained in time O(depth(D) · poly(Q)) per update and conjunctive forward XPath queries in time O(depth(D)·log(width(D))·poly(Q)) per update, where Q  is the size of the query, and depth(D) and width(D) are the nesting depth and maximum number of siblings in the database D, respectively. The auxiliary data structures for maintenance are linear in D  and polynomial in Q  in all these cases.
Materialized View Selection for XQuery Workloads
 In SIGMOD
, 2012
"... The efficient processing of XQuery still poses significant challenges. A particularly effective technique to improve XQuery processing performance consists of using materialized views to answer queries. In this work, we consider the problem of choosing the best views to materialize within a given sp ..."
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Cited by 10 (6 self)
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The efficient processing of XQuery still poses significant challenges. A particularly effective technique to improve XQuery processing performance consists of using materialized views to answer queries. In this work, we consider the problem of choosing the best views to materialize within a given space budget in order to improve the performance of a query workload. The paper is the first to address the view selection problem for queries and views with value joins and multiple return nodes. The challenges we face stem from the expressive power and features of both the query and view languages and from the size of the search space of candidate views to materialize. While the general problem has prohibitive complexity, we propose and study a heuristic algorithm and demonstrate its superior performance compared to the state of the art.
P.: Weak Inclusion for XML Types (full version
 LIFO, Université d’Orléans (2011), http
"... Abstract. Consideringthattheunranked treelanguagesL(G)andL(G ′) are those defined by given nonrecursive XML types G and G ′ , this paper proposes a simple and intuitive method to verify whether L(G) is “approximatively” included in L(G ′). Our approximative criterion consists in weakening the fathe ..."
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Cited by 1 (1 self)
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Abstract. Consideringthattheunranked treelanguagesL(G)andL(G ′) are those defined by given nonrecursive XML types G and G ′ , this paper proposes a simple and intuitive method to verify whether L(G) is “approximatively” included in L(G ′). Our approximative criterion consists in weakening the fatherchildren relationships. Experimental results are discussed, showing the efficiency of our method in many situations. 1
Weak Inclusion for XML Types ⋆
"... Abstract. Considering that the unranked tree languages L(G) and L(G ′ ) are those defined by given nonrecursive XML types G and G ′,this paper proposes a simple and intuitive method to verify whether L(G) is “approximatively ” included in L(G ′). Our approximative criterion consists in weakening th ..."
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Abstract. Considering that the unranked tree languages L(G) and L(G ′ ) are those defined by given nonrecursive XML types G and G ′,this paper proposes a simple and intuitive method to verify whether L(G) is “approximatively ” included in L(G ′). Our approximative criterion consists in weakening the fatherchildren relationships. Experimental results are discussed, showing the efficiency of our method in many situations. 1
Fax: +810117067680Faster BitParallel Algorithms for Unordered PseudoTree Matching and Tree Homeomorphism
, 2010
"... Abstract. In this paper, we consider the unordered pseudotree matching problem, which is a problem of, given two unordered labeled trees P and T, finding all occurrences of P in T via such manyone embeddings that preserve node labels and parentchild relationship. This problem is closely related t ..."
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Abstract. In this paper, we consider the unordered pseudotree matching problem, which is a problem of, given two unordered labeled trees P and T, finding all occurrences of P in T via such manyone embeddings that preserve node labels and parentchild relationship. This problem is closely related to tree pattern matching problem for XPath queries with child axis only. If m> w, we present an efficient algorithm that solves the problem in O(nm log w/w) time using O(hm/w + m log w/w) space and O(m log w) preprocessing on a unitcost arithmetic RAM model with addition, where m is the number of nodes in P, n is the number of nodes in T, h is the height of T, and w is the word length. We also discuss a modification of our algorithm for the unordered tree homeomorphism problem, which corresponds to a tree pattern matching problem for XPath queries with descendant axis only. 1