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ACM Transactions on Database Systems (TODS), Volume 40 Issue 1, March 2015

Editorial: Updates to the Editorial Board
Christian S. Jensen
Article No.: 1e
DOI: 10.1145/2747020

Time- and Space-Efficient Sliding Window Top-k Query Processing
Krešimir Pripužić, Ivana Podnar Žarko, Karl Aberer
Article No.: 1
DOI: 10.1145/2736701

A sliding window top-k (top-k/w) query monitors incoming data stream objects within a sliding window of size w to identify the k highest-ranked objects with respect to a given scoring function over time. Processing of such...

Size Bounds for Factorised Representations of Query Results
Dan Olteanu, Jakub Závodný
Article No.: 2
DOI: 10.1145/2656335

We study two succinct representation systems for relational data based on relational algebra expressions with unions, Cartesian products, and singleton relations: f-representations, which employ algebraic factorisation using distributivity of...

Efficient Computation of the Tree Edit Distance
Mateusz Pawlik, Nikolaus Augsten
Article No.: 3
DOI: 10.1145/2699485

We consider the classical tree edit distance between ordered labelled trees, which is defined as the minimum-cost sequence of node edit operations that transform one tree into another. The state-of-the-art solutions for the tree edit distance are...

Multiple Radii DisC Diversity: Result Diversification Based on Dissimilarity and Coverage
Marina Drosou, Evaggelia Pitoura
Article No.: 4
DOI: 10.1145/2699499

Recently, result diversification has attracted a lot of attention as a means to improve the quality of results retrieved by user queries. In this article, we introduce a novel definition of diversity called DisC diversity. Given a tuning parameter...

Analysis of Schemas with Access Restrictions
Michael Benedikt, Pierre Bourhis, Clemens Ley
Article No.: 5
DOI: 10.1145/2699500

We study verification of systems whose transitions consist of accesses to a Web-based data source. An access is a lookup on a relation within a relational database, fixing values for a set of positions in the relation. For example, a...

Online Updates on Data Warehouses via Judicious Use of Solid-State Storage
Manos Athanassoulis, Shimin Chen, Anastasia Ailamaki, Philip B. Gibbons, Radu Stoica
Article No.: 6
DOI: 10.1145/2699484

Data warehouses have been traditionally optimized for read-only query performance, allowing only offline updates at night, essentially trading off data freshness for performance. The need for 24x7 operations in global markets and the rise of...