169,758 research outputs found
Semantic Data Analysis using Bitmap Indices
No full textAbstract: - The use of bitmap indexes for representing analytical views of user’s data is presented. This approach differs from the conventional definition and use of bitmap indexes in that they are defined not only to index different domain attribute values, but also for pre-computing any legal relational algebra query expression of the user for the analytic purposes. The paper illustrates the meaning of the analytical bitmaps and their application for solving problems of data integration and logical association between data. Furthermore, a fast access algorithm to enquire analytic bitmaps is presented
Extended Semantics of bitmaps for Data Analysis
No full textAbstract: - The contribution of this paper relates to the ability of bitmap indices to support OLAP-oriented queries
and analyses. On one hand, the Bitmap index access method improves the serial data access performance.
On the other hand, the Bitmap index semantics and use allow one to include the definition and management of
complex classes dynamically investigated for analytic purposes. In this novel approach, bitmaps are defined at
a higher abstraction level than the traditional indices and bitmaps. In fact, they allow the analytic or decisional
user to also categorize objects which satisfy any legal relational query
Estimation of Database Unique Values
No full textAbstract: - 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
Analytic-based estimation of query result sizes
No full textAbstract: - 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 so-called 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
Efficiency and effectiveness of data warehousing: a case study
No full textAbstract: - The decisional analysis is a complex, iterative, and exploratory process based on a sequence of
queries issued against the data warehouse. The efficiency of the decisional activity depends on the quality of
the stored data in the data warehouse, while its effectiveness is related to the analysis tools.
In this paper, we discuss both these aspects in the context of a service company, with the aim of analyzing the
trend of railway booking data. In particular, the back-end and front-end software solutions of data warehousing
implementation are presented, which permit to met the customer needs while preserving the desired
requirements of efficiency and effectiveness
Capturing Semantics from Bitmap Indices for Data Analysis
No full textAbstract: - Bitmap indexing is a diffuse approach for processing efficiently complex queries in decision
support activities. Besides this common use of bitmap structures, the use of bitmap indices to represent
analytical views of user’s data is presented here. In this approach, bitmaps can be created and utilized not only
to index different domain attribute values, but also to pre-compute legal relational algebra query expressions
useful for the analytic purposes. According to this approach, problems of data integrations and conceptual
correlations of analytical data can be efficiently solved
Data warehousing system for national railway traffic
No full textimplementation is dealt with. In particular, we present the data warehouse system for the decisional process
based on our national train trasportation data owned by Trenitalia, the Italian main train service company and
customer of the project. We discuss the operational environments interfacing with the data warehouse for data
acquisition and elaboration, and related problems. The systemic aspects we describe refer to both the
feasibility requirements, functionality, and technical architecture of the system. Moreover, a number of
analysis reports actually realized are illustrated as examples of the functionalities provided to the customer.
With the cooperation of the IT solutions provider, the prototype system has been released following primarily
the guidelines of software reuse. In this way, and in order to satisfy all the customer’s requests, the entire
warehouse’s data marts concerning the project are now in the complete re-engineering phase
Using a LCMS Platform to Design a Data Base Course
No full textAbstract: - The choice of a Learning Component Management System (LCMS) to implement online courses in
Computer Science is discussed. The main open source LCMS tools have been taken into account by testing their
basic functionalities. The choice fell on "ATutor", the freeware LCMS multiplatform developed at the
University of Toronto. The structure of a common e-course is presented together with functionalities to manage
lessons and exercises and tools to verify the student's progress. The design and the implementation of an
application real case related to a basic Data Base course is presented
Approximate query processing in decision support system environment
No full textAbstract: - Both the approximate query process and decisional portals are emerging technologies in the decision support system environment. The former tool provides fast execution time for the analysis applications which require access to large amounts of data in the warehouse, by furnishing estimates of summary data with an approximation error acceptable for decision-maker users. The web-based second tool allows managers to monitor the enterprise activities on which decisions have to be taken by means of opportune statistical leds. From the technological viewpoint, such an environment is the result of the integration of data warehouse, query optimizers and Internet technologies
Back-end and front-end solutions for a data warehousing case study
No full textAbstract: - Analysts and decisional users utilize exploratory, complex, but iterative processes based on
sequences of queries formulated against the data warehouse. Whereas the effectiveness of such an activity
is related to analysis tools, its efficiency depends on the current quality of the stored data in the data
warehouse. Here, we describe the case study of analyzing the trend of railway booking data, in the context
of a service provider. In particular, selected back-end and front-end software solutions of data warehousing
realization are illustrated deeply, in order to show how to met the customer’s needs and to preserve the
desired requirements of efficiency and effectiveness
- …
