The analysis, design, and implementation of the data warehouse system for the decisional process ... more The analysis, design, and implementation of the data warehouse system for the decisional process based on the Italian train booking data are presented. Trenitalia, the Italian main train service company, is the customer, and TSF (railway telesystems company) the IT solution provider. In particular, the feasibility requirements, functionality, technical architecture, and product technology are described. Moreover, the guidelines about operational
In this paper, a method for estimating the size of relational query results is proposed. The appr... more In this paper, a method for estimating the size of relational query results is proposed. The approach is based on the estimates of the attribute distinct values. On the basis of our method, a set of parameters, the socalled Canonical Coefficients, can be derived from actual data; they allow us to approximate both the multivariate data distribution and distinct values of attributes. In particular, the capability of analytic method to estimate selectivity factors of relational operations is considered. Some experimental results on real databases are also presented which show the promising performance of our analytic approach.
Counts of database unique values are crucial information in query optimization. Estimating the nu... more Counts of database unique values are crucial information in query optimization. Estimating the number of the distinct values occurs frequently in database queries, due to its importance in selecting query plans. We present a nonparametric method for estimating the database distincts, and, then, the number of distinct values. The method computes few parameters which describe the distribution of distances of distinct values in the attribute value ranges. Tests have been carried out that also show the useful applicability of the method to estimate equi-join selectivity factors.
The Information Technology is an essential support in the decisional process to improve manager' ... more The Information Technology is an essential support in the decisional process to improve manager' phenomena knowledge, that is often approximate and ill-structured. Tools underlying decision support systems (as OLAP systems, data mining, and data warehouses) have a central role in enterprise information systems. In this paper, we present the design and the implementation of a national data warehouse.
There are several benefits that can be reached by developing an academic data warehouse as provid... more There are several benefits that can be reached by developing an academic data warehouse as providing a centralized source of information accessible across different academic units to quickly analyze problems and get satisfactory solutions, supplying the data necessary for developing the Institution's strategic plan, and enabling administrator to make better business decisions based on historical data available in legacy databases. The paper describes the architecture of an academic data warehouse. Examples of analytic reporting are also reported.
The paper examines some common platforms supporting Business Intelligence activities in order to ... more The paper examines some common platforms supporting Business Intelligence activities in order to state evaluation criteria for the system choice. The evaluation considers a software measurement method based on the analysis of the functional complexity of the platforms. The study has been performed on an academic warehouse that uses historical data available in legacy databases. Experimental results are reported which show the advantages and the drawbacks of each considered system.
In decision support activities, it is very important to provide the user with feasible strategies... more In decision support activities, it is very important to provide the user with feasible strategies to answer complex queries, besides furnishing fast query response time. The alternative to the time-consuming scan of huge amounts of data in data warehouses is provided by the use of data reduction for data analysis and a suitable approximate query processing strategy.
The development of a Business Intelligence Application starts with the execution of OLAP queries ... more The development of a Business Intelligence Application starts with the execution of OLAP queries to extract information from data stored in a Data Warehouse. The results of these queries, together with an opportune data representation, offer a deep synthesis of data and help business users to better discover hidden knowledge than using conventional database queries. Nowadays, information discovery is getting more and more important also in academic environments, because internal evaluation teams have to provide the guidelines to improve the quality of both Didactics and Research. In this paper, we present an approach to implement Business Intelligence technology in the University context. The architecture of the data warehouse and examples of analytic queries for the didactics management are also presented and discussed.
We introduce the use of Bitmap indices as very useful tools to represent analytical views of user... more We introduce the use of Bitmap indices as very useful tools to represent analytical views of user's data. This approach differs from the conventional definition and use of bitmaps in that it allows us not only to index different domain attribute values, but also to pre-compute (any) legal relational algebra query expression from the user for analytic purposes. The paper discusses deeply the meaning and our use of analytical bitmaps, and shows some applications using a real context for solving integration and analytic problems.
WSEAS Transactions on Information Science and Applications
A set of evaluation criteria is described and considered for comparing some popular OLAP systems ... more A set of evaluation criteria is described and considered for comparing some popular OLAP systems that support Business Intelligence. These criteria involve critical aspects such as: information delivery, system and user administration, and OLAP queries. The measurement method is based on the functional complexity analysis. Experimental results have been carried out using a data warehouse in academic environment and they allow to evidence the weaknesses and the points of force of each compared system.
The methodologies used in approximate query processing are able to provide fast responses to quer... more The methodologies used in approximate query processing are able to provide fast responses to queries that require high computational time in the decision making process. However, the approximate answers are affected with a small quantity of error. For this reason, it is important to provide also an accuracy of the approximate value, that is, a confidence degree of the approximation. In this paper, we present a probabilistic model that can be used in order to provide the accuracy measure in a methodology based on polynomial approximation. This probabilistic model is a Bayesian network able to estimate the relative error of the approximate answers.
Approximate query processing is often based on analytical methodologies able to provide fast resp... more Approximate query processing is often based on analytical methodologies able to provide fast responses to queries. As a counterpart, the approximate answers are affected with a small quantity of error. Nowadays, these techniques are being exploited in data warehousing environments, because the queries devoted to extract information involve high-cardinality relations and, therefore, require a high computational time. Approximate answers are profitably used in the decision making process, where the total precision is not needed. Thus, it is important to provide decision makers with accuracy estimates of the approximate answers; that is, a measure of how much reliable the approximate answer is. Here, a probabilistic model is presented for providing such an accuracy measure when the analytical methodology used for decisional analyses is based on polynomial approximation. This probabilistic model is a Bayesian network able to estimate the relative error of the approximate answers.
In the last years, data warehousing has got attention from Universities which are now adopting bu... more In the last years, data warehousing has got attention from Universities which are now adopting business intelligence solutions in order to analyze crucial aspects of the academic context. In this paper, we present the architecture of a Business Intelligence system for academic organizations. Then, we illustrate the design process of the data warehouse devoted to the analysis of the main factors affecting the importance and the quality level of every University, such as the evaluation of the Research and the Didactics. The design process we describe is based on a hybrid methodology that is largely automatic and relies on an ontological approach for the integration of the different data sources.
The analysis, design, and implementation of the data warehouse system for the decisional process ... more The analysis, design, and implementation of the data warehouse system for the decisional process based on the Italian train booking data are presented. Trenitalia, the Italian main train service company, is the customer, and TSF (railway telesystems company) the IT solution provider. In particular, the feasibility requirements, functionality, technical architecture, and product technology are described. Moreover, the guidelines about operational
In this paper, a method for estimating the size of relational query results is proposed. The appr... more In this paper, a method for estimating the size of relational query results is proposed. The approach is based on the estimates of the attribute distinct values. On the basis of our method, a set of parameters, the socalled Canonical Coefficients, can be derived from actual data; they allow us to approximate both the multivariate data distribution and distinct values of attributes. In particular, the capability of analytic method to estimate selectivity factors of relational operations is considered. Some experimental results on real databases are also presented which show the promising performance of our analytic approach.
Counts of database unique values are crucial information in query optimization. Estimating the nu... more Counts of database unique values are crucial information in query optimization. Estimating the number of the distinct values occurs frequently in database queries, due to its importance in selecting query plans. We present a nonparametric method for estimating the database distincts, and, then, the number of distinct values. The method computes few parameters which describe the distribution of distances of distinct values in the attribute value ranges. Tests have been carried out that also show the useful applicability of the method to estimate equi-join selectivity factors.
The Information Technology is an essential support in the decisional process to improve manager' ... more The Information Technology is an essential support in the decisional process to improve manager' phenomena knowledge, that is often approximate and ill-structured. Tools underlying decision support systems (as OLAP systems, data mining, and data warehouses) have a central role in enterprise information systems. In this paper, we present the design and the implementation of a national data warehouse.
There are several benefits that can be reached by developing an academic data warehouse as provid... more There are several benefits that can be reached by developing an academic data warehouse as providing a centralized source of information accessible across different academic units to quickly analyze problems and get satisfactory solutions, supplying the data necessary for developing the Institution's strategic plan, and enabling administrator to make better business decisions based on historical data available in legacy databases. The paper describes the architecture of an academic data warehouse. Examples of analytic reporting are also reported.
The paper examines some common platforms supporting Business Intelligence activities in order to ... more The paper examines some common platforms supporting Business Intelligence activities in order to state evaluation criteria for the system choice. The evaluation considers a software measurement method based on the analysis of the functional complexity of the platforms. The study has been performed on an academic warehouse that uses historical data available in legacy databases. Experimental results are reported which show the advantages and the drawbacks of each considered system.
In decision support activities, it is very important to provide the user with feasible strategies... more In decision support activities, it is very important to provide the user with feasible strategies to answer complex queries, besides furnishing fast query response time. The alternative to the time-consuming scan of huge amounts of data in data warehouses is provided by the use of data reduction for data analysis and a suitable approximate query processing strategy.
The development of a Business Intelligence Application starts with the execution of OLAP queries ... more The development of a Business Intelligence Application starts with the execution of OLAP queries to extract information from data stored in a Data Warehouse. The results of these queries, together with an opportune data representation, offer a deep synthesis of data and help business users to better discover hidden knowledge than using conventional database queries. Nowadays, information discovery is getting more and more important also in academic environments, because internal evaluation teams have to provide the guidelines to improve the quality of both Didactics and Research. In this paper, we present an approach to implement Business Intelligence technology in the University context. The architecture of the data warehouse and examples of analytic queries for the didactics management are also presented and discussed.
We introduce the use of Bitmap indices as very useful tools to represent analytical views of user... more We introduce the use of Bitmap indices as very useful tools to represent analytical views of user's data. This approach differs from the conventional definition and use of bitmaps in that it allows us not only to index different domain attribute values, but also to pre-compute (any) legal relational algebra query expression from the user for analytic purposes. The paper discusses deeply the meaning and our use of analytical bitmaps, and shows some applications using a real context for solving integration and analytic problems.
WSEAS Transactions on Information Science and Applications
A set of evaluation criteria is described and considered for comparing some popular OLAP systems ... more A set of evaluation criteria is described and considered for comparing some popular OLAP systems that support Business Intelligence. These criteria involve critical aspects such as: information delivery, system and user administration, and OLAP queries. The measurement method is based on the functional complexity analysis. Experimental results have been carried out using a data warehouse in academic environment and they allow to evidence the weaknesses and the points of force of each compared system.
The methodologies used in approximate query processing are able to provide fast responses to quer... more The methodologies used in approximate query processing are able to provide fast responses to queries that require high computational time in the decision making process. However, the approximate answers are affected with a small quantity of error. For this reason, it is important to provide also an accuracy of the approximate value, that is, a confidence degree of the approximation. In this paper, we present a probabilistic model that can be used in order to provide the accuracy measure in a methodology based on polynomial approximation. This probabilistic model is a Bayesian network able to estimate the relative error of the approximate answers.
Approximate query processing is often based on analytical methodologies able to provide fast resp... more Approximate query processing is often based on analytical methodologies able to provide fast responses to queries. As a counterpart, the approximate answers are affected with a small quantity of error. Nowadays, these techniques are being exploited in data warehousing environments, because the queries devoted to extract information involve high-cardinality relations and, therefore, require a high computational time. Approximate answers are profitably used in the decision making process, where the total precision is not needed. Thus, it is important to provide decision makers with accuracy estimates of the approximate answers; that is, a measure of how much reliable the approximate answer is. Here, a probabilistic model is presented for providing such an accuracy measure when the analytical methodology used for decisional analyses is based on polynomial approximation. This probabilistic model is a Bayesian network able to estimate the relative error of the approximate answers.
In the last years, data warehousing has got attention from Universities which are now adopting bu... more In the last years, data warehousing has got attention from Universities which are now adopting business intelligence solutions in order to analyze crucial aspects of the academic context. In this paper, we present the architecture of a Business Intelligence system for academic organizations. Then, we illustrate the design process of the data warehouse devoted to the analysis of the main factors affecting the importance and the quality level of every University, such as the evaluation of the Research and the Didactics. The design process we describe is based on a hybrid methodology that is largely automatic and relies on an ontological approach for the integration of the different data sources.
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Papers by Ezio Lefons