On-line analytical processing in distributed data warehouses

The concepts of 'data warehousing' and 'on-line analytical processing' have seen a growing interest in the research and commercial product community. Today, the trend moves away from complex centralized data warehouses to distributed data marts integrated in a common conceptual schema. However, as the first part of this paper demonstrates, there are many problems and little solutions for large distributed decision support systems in worldwide operating corporations. After showing the benefits and problems of the distributed approach, this paper outlines possibilities for achieving performance in distributed online analytical processing. Finally, the architectural framework of the prototypical distributed OLAP system CUBESTAR is outlined

Clustering-Based Materialized View Selection in Data Warehouses

Materialized view selection is a non-trivial task. Hence, its complexity must be reduced. A judicious choice of views must be cost-driven and influenced by the workload experienced by the system. In this paper, we propose a framework for materialized view selection that exploits a data mining technique (clustering), in order to determine clusters of similar queries. We also propose a view merging algorithm that builds a set of candidate views, as well as a greedy process for selecting a set of views to materialize. This selection is based on cost models that evaluate the cost of accessing data using views and the cost of storing these views. To validate our strategy, we executed a workload of decision-support queries on a test data warehouse, with and without using our strategy. Our experimental results demonstrate its efficiency, even when storage space is limited

Comparative Analysis of Decision Tree Algorithms for Data Warehouse Fragmentation

One of the main problems faced by Data Warehouse designers is fragmentation.Several studies have proposed data mining-based horizontal fragmentation methods.However, not exists a horizontal fragmentation technique that uses a decision tree. This paper presents the analysis of different decision tree algorithms to select the best one to implement the fragmentation method. Such analysis was performed under version 3.9.4 of Weka, considering four evaluation metrics (Precision, ROC Area, Recall and F-measure) for different selected data sets using the Star Schema Benchmark. The results showed that the two best algorithms were J48 and Random Forest in most cases; nevertheless, J48 was selected because it is more efficient in building the model.One of the main problems faced by Data Warehouse designers is fragmentation.Several studies have proposed data mining-based horizontal fragmentation methods.However, not exists a horizontal fragmentation technique that uses a decision tree. This paper presents the analysis of different decision tree algorithms to select the best one to implement the fragmentation method. Such analysis was performed under version 3.9.4 of Weka, considering four evaluation metrics (Precision, ROC Area, Recall and F-measure) for different selected data sets using the Star Schema Benchmark. The results showed that the two best algorithms were J48 and Random Forest in most cases; nevertheless, J48 was selected because it is more efficient in building the model

Towards Comparative Analysis of Resumption Techniques in ETL

Data warehouses are loaded with data from sources such as operational data bases. Failure of loading process or failure of any of the process such as extraction or transformation is expensive because of the non-availability of data for analysis. With the advent of e-commerce and many real time application analysis of data in real time becomes a norm and hence any misses while the data is being loaded into data warehouse needs to be handled in an efficient and optimized way. The techniques to handle failure of process to populate the data are very much important as the actual loading process. Alternative arrangement needs to be made for in case of failure so that processes of populating the data warehouse are done in time. This paper explores the various ways through which a failed process of populating the data warehouse could be resumed. Various resumption techniques are compared and a novel block based technique is proposed to improve one of the existing resumption techniques

Business intelligence-centered software as the main driver to migrate from spreadsheet-based analytics

Internship Report presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Knowledge Management and Business IntelligenceNowadays, companies are handling and managing data in a way that they weren’t ten years ago. The data deluge is, as a mere consequence of that, the constant day-to-day challenge for them - having to create agile and scalable data solutions to tackle this reality. The main trigger of this project was to support the decision-making process of a customer-centered marketing team (called Customer Voice) in the Company X by developing a complete, holistic Business Intelligence solution that goes all the way from ETL processes to data visualizations based on that team’s business needs. Having this context into consideration, the focus of the internship was to make use of BI, ETL techniques to migrate their data stored in spreadsheets — where they performed data analysis — and shift the way they see the data into a more dynamic, sophisticated, and suitable way in order to help them make data-driven strategic decisions. To ensure that there was credibility throughout the development of this project and its subsequent solution, it was necessary to make an exhaustive literature review to help me frame this project in a more realistic and logical way. That being said, this report made use of scientific literature that explained the evolution of the ETL workflows, tools, and limitations across different time periods and generations, how it was transformed from manual to real-time data tasks together with data warehouses, the importance of data quality and, finally, the relevance of ETL processes optimization and new ways of approaching data integrations by using modern, cloud architectures

Augmenting data warehousing architectures with hadoop

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Information Systems and Technologies ManagementAs the volume of available data increases exponentially, traditional data warehouses struggle to transform this data into actionable knowledge. Data strategies that include the creation and maintenance of data warehouses have a lot to gain by incorporating technologies from the Big Data’s spectrum. Hadoop, as a transformation tool, can add a theoretical infinite dimension of data processing, feeding transformed information into traditional data warehouses that ultimately will retain their value as central components in organizations’ decision support systems. This study explores the potentialities of Hadoop as a data transformation tool in the setting of a traditional data warehouse environment. Hadoop’s execution model, which is oriented for distributed parallel processing, offers great capabilities when the amounts of data to be processed require the infrastructure to expand. Horizontal scalability, which is a key aspect in a Hadoop cluster, will allow for proportional growth in processing power as the volume of data increases. Through the use of a Hive on Tez, in a Hadoop cluster, this study transforms television viewing events, extracted from Ericsson’s Mediaroom Internet Protocol Television infrastructure, into pertinent audience metrics, like Rating, Reach and Share. These measurements are then made available in a traditional data warehouse, supported by a traditional Relational Database Management System, where they are presented through a set of reports. The main contribution of this research is a proposed augmented data warehouse architecture where the traditional ETL layer is replaced by a Hadoop cluster, running Hive on Tez, with the purpose of performing the heaviest transformations that convert raw data into actionable information. Through a typification of the SQL statements, responsible for the data transformation processes, we were able to understand that Hadoop, and its distributed processing model, delivers outstanding performance results associated with the analytical layer, namely in the aggregation of large data sets. Ultimately, we demonstrate, empirically, the performance gains that can be extracted from Hadoop, in comparison to an RDBMS, regarding speed, storage usage and scalability potential, and suggest how this can be used to evolve data warehouses into the age of Big Data

From access and integration to mining of secure genomic data sets across the grid

The UK Department of Trade and Industry (DTI) funded BRIDGES project (Biomedical Research Informatics Delivered by Grid Enabled Services) has developed a Grid infrastructure to support cardiovascular research. This includes the provision of a compute Grid and a data Grid infrastructure with security at its heart. In this paper we focus on the BRIDGES data Grid. A primary aim of the BRIDGES data Grid is to help control the complexity in access to and integration of a myriad of genomic data sets through simple Grid based tools. We outline these tools, how they are delivered to the end user scientists. We also describe how these tools are to be extended in the BBSRC funded Grid Enabled Microarray Expression Profile Search (GEMEPS) to support a richer vocabulary of search capabilities to support mining of microarray data sets. As with BRIDGES, fine grain Grid security underpins GEMEPS