The Department of Computer Science at the University of Cyprus cordially invites you to the Colloquium entitled:

Adaptive Join Processing


Speaker: Dr. Vasilis A. Vassalos
Affiliation: Athens Univ. of Economics and Business, Greece
Category: Colloquium
Location: Room 148, Faculty of Pure and Applied Sciences (FST-01), 1 University Avenue, 2109 Nicosia, Cyprus (directions)
Date: Thursday, February 12th, 2009
Time: 16:30 - 17:30 EET
Host: Demetris Zeinalipour (dzeina AT

Adaptive join algorithms have recently attracted a lot of attention in emerging applications where data is provided by autonomous data sources through heterogeneous network environments. Their main advantage over traditional join techniques is that they can start producing join results as soon as the first input tuples are available, thus improving pipelining by smoothing join result production and by masking source or network delays. I will describe Double Index NEstedloops Reactive join (DINER), a new adaptive join algorithm for result rate maximization. DINER combines two key elements: an intuitive flushing policy that aims to increase the productivity of in-memory tuples in producing results during the online phase of the join, and a novel re-entrant join technique that allows the algorithm to rapidly switch between processing in-memory and disk-resident tuples, thus better exploiting temporary delays when new data is not available. I will present experimental results using real and synthetic data sets that show that DINER outperforms previous adaptive join algorithms in producing result tuples at a significantly higher rate, while making better use of the available memory.

Short Bio:
Prof. Vasilis Vassalos (PhD in CS, Stanford University, 2000) is an Associate Professor in the Department of Informatics at AUEB. His research is on infrastructure and algorithmic issues for the integration of data and Web services in different environments, including XML query processing, specification-driven interface generation, adaptive query processing, and query rewriting using views. He is also working on sensor data management. Vassalos is the recipient of numerous awards, including a Marie Curie Outgoing International Fellowship for 2007-2008, and has been Principal Investigator for 8 funded research and advanced development projects since his arrival at AUEB in 2004. He is the author of over 25 technical publications and two US patents. He is or has been a member of the Program Committees of numerous international conferences, including SIGMOD 2008 and VLDB 2007. He is the co-founder of software company Enosys Software (sold to BEA Systems in 2003), maker of the first XQuery-based data integration platform and XQuery engine. Before joining AUEB he was an Assistant Professor of Information Systems at the Stern School of Business at NYU.

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Sponsor: The CS Colloquium Series is supported by a generous donation from Microsoft