Ioannis Koumarelas, PhD
Ioannis Koumarelas, PhD
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Flexible Partitioning for Selective Binary Theta-Joins in a Massively Parallel Setting
Efficient join processing plays an important role in big data analysis. In this work, we focus on generic theta joins in a massively parallel environment, such as MapReduce and Spark.
Ioannis Koumarelas
,
Athanasios Naskos
,
Anastasios Gounaris
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Binary Theta-Joins using MapReduce: Efficiency Analysis and Improvements
We deal with binary theta-joins in a MapReduce environment, and we make two contributions. First, we show that the best known algorithm …
Ioannis Koumarelas
,
Athanasios Naskos
,
Anastasios Gounaris
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Integrating similarity and dissimilarity notions in recommenders
Collaborative recommenders rely on the assumption that similar users may exhibit similar tastes while content-based ones favour items that found to be similar with the items a user likes. Weak related entities, which are often considered to be useful, are neglected by those similarity-driven recommenders. To take advantage of this neglected information, we introduce a novel dissimilarity-based recommender that bases its estimations on degrees of dissimilarities among items’ attributes.
Christos Zigkolis
,
Savvas Karagiannidis
,
Ioannis Koumarelas
,
Athena Vakali
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