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Displaying 1-16 out of 16 total
Fast Accurate Summary Warehouses with Distributed Summaries
Found in: Database Engineering and Applications Symposium, International
By Pedro Furtado, Joao Pedro Costa
Issue Date:July 2003
pp. 370
<p>Large Data warehouses (DW) put a major challenge in what concerns performance and scalability, as users request instant answers to their queries. Traditional solutions relying on very expensive architectures and structures cannot turn every comple...
 
The BofS Solution to Limitations of Approximate Summaries
Found in: Database Systems for Advanced Applications, International Conference on
By Pedro Furtado, João Pedro Costa
Issue Date:March 2003
pp. 223
Data warehouses are of crucial importance to decision-making in competitive organizations. The fact that they store enormous quantities of data is a challenge in what concerns performance and scalability, as users request instant answers. None of the tradi...
 
Poster session: Towards a QoS-aware DBMS
Found in: Data Engineering Workshops, 22nd International Conference on
By Joao Pedro Costa, Pedro Furtado
Issue Date:April 2008
pp. 50-55
Quality of service is a key issue in current and future computer systems. Applications run on systems and typically access a backend DBMS which doesn’t provide performance-related QoS guarantees, and whose resources are constrained. Throughput increases wi...
 
Time-Stratified Sampling for Approximate Answers to Aggregate Queries
Found in: Database Systems for Advanced Applications, International Conference on
By João Pedro Costa, Pedro Furtado
Issue Date:March 2003
pp. 215
In large data warehousing environments, it is often advantageous to provide fast, approximate answers to complex aggregate queries based on samples. However, uniformly extracted samples often do not guarantee acceptable accuracy in grouping interval estima...
 
Integrity for Electronic Patient Record Reports
Found in: Computer-Based Medical Systems, IEEE Symposium on
By Ana Ferreira, Ricardo Correia, Luis Antunes, Ernesto Palhares, Pedro Marques, Pedro Costa, Altamiro da Costa Pereira
Issue Date:June 2004
pp. 4
The use of an EPR within a hospital is essential in order to integrate and centralize patient healthcare information. With the introduction of this technology information security becomes an important issue, moreover when the EPR integrates several exam re...
 
On the Performance of Byzantine Fault-Tolerant MapReduce
Found in: IEEE Transactions on Dependable and Secure Computing
By Pedro Costa,Marcelo Pasin,Alysson Neves Bessani,Miguel P. Correia
Issue Date:September 2013
pp. 301-313
MapReduce is often used for critical data processing, e.g., in the context of scientific or financial simulation. However, there is evidence in the literature that there are arbitrary (or Byzantine) faults that may corrupt the results of MapReduce without ...
 
Evaluation Criteria for Cloud Services
Found in: 2013 IEEE 6th International Conference on Cloud Computing (CLOUD)
By Pedro Costa,Joao Paulo Santos,Miguel Mira Da Silva
Issue Date:June 2013
pp. 598-605
Cloud Computing is revolutionizing the Information Technology (IT) industry by enabling organizations to have flexible costs by buying a service instead of owning their assets. Nevertheless, decision makers (DM) in IT organizations have difficulties in eva...
 
TEEPA: a timely-aware elastic parallel architecture
Found in: Proceedings of the 16th International Database Engineering & Applications Sysmposium (IDEAS '12)
By João Pedro Costa, José Cecilio, Pedro Furtado, Pedro Martins
Issue Date:August 2012
pp. 24-31
Parallel Shared-Nothing architectures are frequently used to handle large star-schema Data Warehouses (DW). The continuous increase in data volume and the star-schema storage organization introduce severe limitations to scalability due to the well-known pa...
     
Byzantine Fault-Tolerant MapReduce: Faults are Not Just Crashes
Found in: Cloud Computing Technology and Science, IEEE International Conference on
By Pedro Costa,Marcelo Pasin,Alysson N. Bessani,Miguel Correia
Issue Date:December 2011
pp. 32-39
MapReduce is often used to run critical jobs such as scientific data analysis. However, evidence in the literature shows that arbitrary faults do occur and can probably corrupt the results of MapReduce jobs. MapReduce runtimes like Hadoop tolerate crash fa...
 
A predictable storage model for scalable parallel DW
Found in: Proceedings of the 15th Symposium on International Database Engineering & Applications (IDEAS '11)
By Joao Pedro Costa, Jose Cecilio, Pedro Furtado, Pedro Martins
Issue Date:September 2011
pp. 26-33
Star schema model, has been widely used as the facto DW storage organization on RDBMS. Business measures are stored in a central fact table along with a set of foreign keys referencing dimension tables. While this storage organization offers a good trade-o...
     
Dependability Benchmarking Using Software Faults: How to Create Practical and Representative Faultloads
Found in: Pacific Rim International Symposium on Dependable Computing, IEEE
By Pedro Costa,João Gabriel Silva,Henrique Madeira
Issue Date:November 2009
pp. 289-294
The faultload is one of the most critical components of a dependability benchmark. It should embody a repeatable, portable, representative and generally accepted fault set. Concerning software faults, the definition of that kind of faultloads is particular...
 
Webstorm: mixing brainstorming in the web to produce art
Found in: Proceedings of the 26th annual ACM international conference on Design of communication (SIGDOC '08)
By Carlos J. Costa, Pedro Costa, Pedro Duarte
Issue Date:September 2008
pp. 1-2
The Internet has always been seen by artists as a new form of expression, the non material nature, the absence of frontiers and achieving new public give rise to a new type of art. The artistic environment of contemporary art is achieved as a fundamental b...
     
Developing a game in the context of an open source community
Found in: Proceedings of the 2013 International Conference on Information Systems and Design of Communication (ISDOC '13)
By Carlos J. Costa, Pedro Costa
Issue Date:July 2013
pp. 108-112
The purpose of this paper is to present a game development approach in a context of an open source community. The problem of community creation and management is an important issue in this context. Identifying who is involved, what are their motivations, a...
     
A peace war game application
Found in: Proceedings of the 2011 Workshop on Open Source and Design of Communication (OSDOC '11)
By Carlos J. Costa, Pedro Costa
Issue Date:July 2011
pp. 71-74
In this paper we present a game. In order to develop this game, we use iterative prisoner dilemma. Concepts involved in the development of this game, allow creating a game with some potential advantages. In fact, it may be useful to learn how market works,...
     
On the Feasibility of Byzantine Fault-Tolerant MapReduce in Clouds-of-Clouds
Found in: 2012 IEEE 31st International Symposium on Reliable Distributed Systems (SRDS)
By Miguel Correia,Pedro Costa,Marcelo Pasin,Alysson Bessani,Fernando Ramos,Paulo Verissimo
Issue Date:October 2012
pp. 448-453
MapReduce is a framework for processing large data sets largely used in cloud computing. MapReduce implementations like Hadoop can tolerate crashes and file corruptions, but there is evidence that general arbitrary faults do occur and can affect the correc...
   
Evaluating web site design
Found in: Proceedings of the 26th annual ACM international conference on Design of communication (SIGDOC '08)
By Pedro Costa
Issue Date:September 2008
pp. 1-2
The webpage aesthetics is one of the factors that affect the way people are attracted to a site. But two questions emerge: how can we improve a webpage's aesthetics and how can we evaluate this item? In order to solve this problem, we identified some of th...
     
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