Bartosz Bębel

Poznan University of Technology · Institute of Computing Science

Assuring high quality of data stored in information systems (ISs) is challenging and it is one of concerns of companies. Typically, data stored in ISs are not free from errors, which include among others wrong and missing values as well as duplicates. Data deduplication has received a lot of attention from the research community. The research effor...

Ubiquitous devices and applications generate data that are naturally ordered by time. Thus elementary data items can form sequences. The most popular way of analyzing sequences is searching for patterns. To this end, sequential pattern discovery techniques were proposed in some research contributions and implemented in a few database systems, e.g.,...

Ubiquitous devices and applications generate data, whose natural feature is order. Most of the commercial software and research prototypes for data analytics allow to analyze set oriented data, neglecting their order. However, by analyzing both data and their order dependencies, one can discover new business knowledge. Few solutions in this field h...

Numerous nowadays applications generate huge sets of data, whose natural feature is order, e.g,. sensor installations, RFID devices, workflow systems, Website monitors, health care applications. By analyzing the data and their order dependencies one can acquire new knowledge. However, nowadays commercial BI technologies and research prototypes allo...

Nowadays business intelligence technologies allow to analyze mainly set oriented data, without considering order dependencies between data. Few approaches to analyzing data of sequential order have been proposed so far. Nonetheless, for storing and manipulating sequential data the approaches use either the relational data model or its extensions. W...

Recent appearance of the a type of OLAP analysis, the sequential OLAP (or SOLAP) has caused the need for new index structures which support new types of analytical queries. An integral part of processing SOLAP queries is finding sequences which match a user-specified pattern. We call such queries \emph{subsequence pattern queries}. The contribution...

In this paper we address problems of managing data warehouses (DWs) that evolve in time and we demonstrate that transactional maintenance of evolving DWs is inevitable. To this end, we propose a nested transaction model. In this model we define 5 types of transactions each of which is responsible for certain tasks. The tasks and properties of these...

A data warehouse (DW) is a large centralized database that stores data integrated from multiple, usually heterogeneous external data sources (EDSs). DW content is processed by so called On-Line Analytical Processing applications, that analyze business trends, discover anomalies and hidden dependencies between data. These applications are part of de...

This paper addresses problems of the evolution of data warehouse schema and dimensions. In order to handle the evolution, we apply a multiversion data warehouse (MVDW). In this paper we discuss real world cases illustrating a DW evolution and show how to apply the MVDW in order to handle the cases.

Streszczenie Istotnym czynnikiem branym pod uwagę przy wyborze technologii składowania i przetwarzania danych w hurtowni danych jest wydajność. Do dyspozycji stoją dwa rozwiązania: wykorzystanie relacyjnego serwera bazy danych ogólnego przezna-czenia (ROLAP) albo dedykowanego serwera przetwarzania danych wielowymiarowych (MOLAP). System Oracle od k...

A data warehouse (DW) is supplied with data that come from external data sources (EDSs) that are production systems. EDSs, which are usually autonomous, often change not only their contents but also their structures. The evolution of external data sources has to be reflected in a DW that uses the sources. Traditional DW systems offer a limited supp...

A data warehouse (DW) is a database that integrates data from external data sources (EDSs) for the purpose of advanced analysis. EDSs are production systems that often change not only their contents but also their structures. The evolution of EDSs has to be reflected in a DW that integrates the sources. Traditional DW systems offer a limited suppor...

A data warehouse (DW) provides an information for analytical processing, decision making, and data mining tools. On the one hand, the structure and content of a data warehouse reflects a real world, i.e. data stored in a DW come from real production systems. On the other hand, a DW and its tools may be used for predicting trends and simulating a vi...

Object-relational data warehousing systems are more and more often applied to the integration and analysis of complex data. For such warehouses, the application of materialized object-oriented views is promising. Such views are able to: (1) integrate not only data of complex structure but also manage the behavior of data, i.e. methods, (2) transfor...

The application of materialised object-oriented views in object-relational data warehousing systems is promising. In this paper we propose a novel technique for the materialisation of method results in object-oriented views, called hierarchical materialisation. When an object used to materialise the result of method m is updated, then m has to be r...

In several database applications sets of related queries are submitted together to be processed as a single unit. In all these cases the queries usually have some degree of overlap, i.e. may have common subqueries. Therefore a significant performance improvement can be obtained by optimizing and executing the entire group of queries as a whole, thu...

Abstrakt Oracle Business Intelligence Beans (w skrócie BI Beans) to zestaw komponentów JavaBeans, pozwalających na prostą i szybką implementację w aplikacji bazodanowej zaawansowanych mechanizmów przetwarzania analitycznego OLAP. Komponenty BI Beans dzielą się na trzy kategorie: komponenty prezentacyjne, takie jak wykresy i tabele do prezentacji da...

Abstrakt Replikacja to proces kopiowania i utrzymywania obiektów (np. tabel) w po³¹czonych bazach danych, tworz¹cych jedno oerodowisko. Artyku³ omawia podstawowe obiekty, bior¹ce udzia³ w replikacji: tabele, pakiety, migawki, grupy odoewie¿ania i inne. Porusza zagadnie-nia zaawansowanej replikacji (opcji SZBD Oracle w wersji Enterprise): ró¿ne typy...