An Alternative Relational OLAP Modeling Approach

Schema design is one of the fundamentals in database theory and practice as well. In this paper, we discuss the problem of locally valid dimensional attributes in a classification hierarchy of a typical OLAP scenario. In a first step, we show that the traditional star and snowflake schema approach is not feasible in this very natural case of a hierarchy. Therefore, we sketch two alternative modeling approaches resulting in practical solutions and a seamless extension of the traditional star and snowflake schema approach: In a pure relational approach, we replace each dimension table of a star / snowflake schema by a set of views directly reflecting the classification hierarchy. The second approach takes advantage of the object-relational extensions. Using object-relational techniques in the context for the relational representation of a multidimensional OLAP scenario is a novel approach and promises a clean and smooth schema design

Query optimization by using derivability in a data warehouse environment

Materialized summary tables and cached query results are frequently used for the optimization of aggregate queries in a data warehouse. Query rewriting techniques are incorporated into database systems to use those materialized views and thus avoid the access of the possibly huge raw data. A rewriting is only possible if the query is derivable from these views. Several approaches can be found in the literature to check the derivability and find query rewritings. The specific application scenario of a data warehouse with its multidimensional perspective allows the consideration of much more semantic information, e.g. structural dependencies within the dimension hierarchies and different characteristics of measures. The motivation of this article is to use this information to present conditions for derivability in a large number of relevant cases which go beyond previous approaches

On the problem of generating common predecessors

Using common subexpressions to speed up a set of queries is a well known and long studied problem. However, due to the isolation requirement, operating a database in the classic transactional way does not offer many applications to exploit the benefits of simultaneously computing a set of queries. In the opposite, many applications can be identified in the context of data warehousing, e. g. optimizing the incremental maintenance process of multiple dependent materialized views or the generation of application specific data marts. In the paper we discuss the problem whether it is always advisable to generate the most complete common predecessor for a given set of queries or to restrict a predecessor to a subset of all possible base tables. As we will see, this question cannot be answered without having knowledge about the cardinality of queries after aggregation. However, if we can rely on this information, we can come up with an optimal predecessor for a common set of queries

Contracting in the days of eBusiness

Putting electronic business on a sound foundation --- model theoretically as well as technologically --- has to be seen as a central challenge for research as well as for commercial development. This paper concentrates on the discovery and the negotiation phase of concluding an agreement based on a contract. We present a methodology how to come seamlessly from a many-to-many relationship in the discovery phase to a one-to-one relationship in the contract negotiation phase. Making the content of the contracts persistent is achieved by reconstructing contract templates by means of mereologic (logic of the whole-part relation). Possibly nested sub-structures of the contract template are taken as a basis for negotiation in a dialogical way. For the negotiation itself the contract templates are extended by implications (logical) and sequences (topical)

Nutzung von Datenbankdiensten in Data-Warehouse-Anwendungen

Zentral für eine effiziente Analyse der in Data-Warehouse-Systemen gespeicherten Daten ist das Zusammenspiel zwischen Anwendung und Datenbanksystem. Der vorliegende Artikel klassifiziert und diskutiert unterschiedliche Wege, Data-Warehouse-Anwendungen mit dem Datenbanksystem zu koppeln, um komplexe OLAP-Szenarien zur Berechnung dem Datenbankdienst zu überlassen. Dabei werden vier unterschiedliche Kategorien, die Spracherweiterung (SQL), die anwendungsspezifische Sprachneuentwicklung (MDX), die Nutzung spezifischer Objektmodelle (JOLAP) und schließlich der Rückgriff auf XML-basierte WebServices (XCube) im einzelnen diskutiert und vergleichend gegenübergestellt.The connection of the applications and the underlying database system is crucial for performing analyses efficiently within a data warehouse system. This paper classifies and discusses different methods to bring data warehouse applications logically close to the underlying database system so that the computation of complex OLAP scenarios may be performed within the database system and not outside at the application. In detail, four different categories ranging from language extension (SQL) over the design of a new query language (MDX) and using special object models (JOLAP) to the use of XML-based WebServices are discussed and compared in detail

Xcube: XML for data warehouses

ABSTRACT Data warehouse systems are nowadays a well known and widely spread approach for supporting management decisions. In several companies or even across companies the idea of integrating several data warehouses into a virtual or federated data warehouse is of growing interest. But the technical and semantic problems are very demanding. An essential part for solving this problem is a standardized, vendor independent format for describing multidimensional data. This paper introduces XCube, a family of XML based document templates to exchange data warehouse data, i.e. data cubes, over any kind of network. XCube is organized in a modular fashion, so the multidimensional schema, the descriptions of the single dimensions and the fact data itself can be transmitted in separate steps. In addition to the describing formats XCube also offers two kinds of dynamic document types that can be used to explore the (multidimensional) content of another warehouse in a vendor independent way. They are primarily meant to reduce the amount of data transferred over the networ

Analysis of potentially chemopreventive constituents of apple juice

Ziel dieser Arbeit war es, unbekannte (Minor)-Komponenten aus Apfelsaft zu identifizieren und deren Beitrag zur chemopräventiven Wirkung des Saftes zu bestimmen. Deren Motivation war begründet, dass bisher identifizierte niedermolekulare phenolische Verbindungen als Mischung nicht das gleiche chemopräventive Potential wie ein polyphenolangereicherter Apfelsaftextrakt aufgewiesen hatten. Zunächst wurden sieben Apfelsäfte verschiedener Erntejahre sowie 14 polyphenolangereicherte Saftextrakte auf ihre stoffliche Zusammensetzung hin untersucht. Dabei zeigte sich, dass die Polyphenolzusammensetzung der Apfelsäfte und -extrakte sowohl zwischen verschiedenen Produktionsjahren als auch abhängig von der verwendeten Produktionstechnologie stark variierte. Insbesondere der durch enzymatische Tresterverflüssigung erhaltene Saftextrakt (AE03B) wies eine deutliche Anreicherung an Quercetin- und Phloretinglycosiden sowie eine Abreicherung an phenolischen Säuren auf. Die Klärung von trüben Säften hatte keinen signifikanten Einfluss auf die Verteilung niedermolekularer Flavonoide. Tendenziell waren die Extrakte der trüben Säfte leicht an Phloretinglycosiden abgereichert. Im Gegensatz dazu wurde eine leichte Anreicherung der phenolischen Säuren in den untersuchten klaren Säften im Vergleich zu den trüben festgestellt. Der Gehalt hochmolekularer Procyanidine variierte in den untersuchten Säften und Saftextrakten produktions- und sortenbedingt ebenfalls stark. An klaren und trüben Säften einer Charge wurde eine signifikante Abnahme sowohl des Gehaltes als auch des mittleren Polymerisationsgrades durch den Klärungsprozess nachgewiesen. Ferner zeigten Reinfruchtsäfte aus Mostapfelsorten höhere Gehalte und mittlere Polymerisationsgrade als verschnittene Apfelsäfte mit einem Anteil an Tafeläpfeln. Als nicht phenolische Bestandteile wurden in den Säften und Saftextrakten (R)-Oktan-1,3-diol, (R)-5-(Z)-Okten-1,3-diol, 3-Hydroxy-2-pyron und 3-Hydroxy-beta-damascon detektiert. Zwei ausgewählte Saftextrakte aus den Jahren 2004 und 2006 wurden unter Zuhilfenahme unterschiedlicher präparativer Trennmethoden fraktioniert. Im Verlauf der Auftrennung wurden durch präparative Isolierung Quercetin, Qercetin-3-O-glucosid, Quercetin-3-O-galactosid, 3-Hydroxyphloretin-2’-glucosid, 3-Hydroxyphloretin-2’-xyloglucosid, Phloretin-2’-xyloglucosid und Phloretin-2’,4’-diglucosid erhalten. Die erhaltenen Subfraktionen und Reinstoffe wurden in vitro auf ihre Hemmwirkung der Proteintyrosinkinase (PTK) des epidermalen Wachstumsfaktor-Rezeptor (EGFR) untersucht. Darüber hinaus wurden die antioxidativen (DPPH, ORAC, X/XO), die antiinflammatorischen und antihormonellen (COX-1, CYP19) Eigenschaften sowie die Fähigkeit zur Modulation des Fremdstoffmetabolismus (CYP1A, QR) überprüft. Die Procyanidine des Apfels erwiesen sich in Abhängigkeit ihres Polymerisationsgrades als starke Inhibitoren der PTK des EGFR. So zeigten ausschließlich hochpolymere Procyanidine enthaltende Fraktionen (NP.4 und NP.5) eine deutlich stärkere Hemmung als Fraktionen, die nur aus niedermolekularen phenolischen Verbindungen zusammengesetzt waren. Auf die Enzyme Cytochrom P450 1A und Aromatase (CYP19) hatten die Procyanidine ebenfalls einen entscheidenden Einfluss. Die antioxidativen Eigenschaften der Apfelsaftextrakte waren sowohl vom Gehalt polymerer Procyanidine als auch von dem niedermolekularer Polyphenole abhängig. Die für die Apfelsaftextrakte nachgewiesenen Radikalfängereigenschaften und die Hemmung der Superoxidanionbildung wurden für beide Gruppen ebenfalls bestätigt. Dahingegen wurden Peroxylradikale im ORAC-Test fast ausschließlich von niedermolekularen Verbindungen abgefangen. Die 3-Hydroxyphloretin(glycoside) zeigten, mit Ausnahme des Xyloglucosids, am EGFR eine stärkere inhibitorische Wirkung als die entsprechenden Phloretin(glycoside). Die Untersuchung der Enzyme des Fremdstoffmetabolismus zeigte ein uneinheitliches Bild. So war Phloretin ein effektiverer Hemmstoff der CYP1A im Vergleich zum 3-Hydroxyphloretin. Bei den Glycosiden zeigten 3-Hydroxyphloretin-2’-glucosid die etwas bessere Wirkung. Ähnlich verhielt es sich bei der antioxidativen Kapazität. Die 3-Hydroxyphloretin(glycoside) wiesen im DPPH und X/XO-Assay eine größere Aktivität auf. Hydroxylperoxidradikale wurden nur durch das dihydroxylierte freie Aglykon besser abfangen. Weiterhin wurde mit 3-Hydroxy-beta-damascon erstmals ein hochpotenter Induktor der Chinonreduktase in Apfelsaft identifiziert. Die in dieser Arbeit erlangten Erkenntnisse hinsichtlich der neu identifizierten bioaktiven Inhalsstoffe leisten einen Beitrag zum besseren Verständnis der potentiell chemopräventiven Wirkungen von (trüben) Apfelsäften. Ferner ist die Quantifizierung dieser Substanzen in technologisch unterschiedlich behandelten Säften für weiterführende Studien von Relevanz.The aim of the present work was to identify new (minor) components in apple juice and to determine their contribution to the chemopreventive potential of the juice. Motivation for this work were previous findings, demonstrating that known, low-molecular phenolic compounds, as a mixture, did not exhibit the same chemopreventive potential as polyphenol-enriched apple juice extract. Therefore seven apple juices of different years of harvest as well as 14 polyphenol-enriched apple juice extracts have been examined with respect to their chemical composition. It was shown, that the polyphenol composition of the apple juices and -extracts differed markedly, depending both on the year of production and the production technology applied. Most notably, juice extract AE03B, produced by enzymatic pomace treatment, showed a significant enrichment of quercetin and phloretin glycosides as well as a depletion of phenolic acids. Clarification of cloudy apple juices had no significant effect on the composition of the low molecular polyphenol fraction. By tendency, extracts obtained from cloudy juices contained slightly less phloretin glycosides compared to clear juice extracts, whereas clear juices showed a low enrichment of phenolic acids compared to cloudy juices. High variations in high molecular procyanidins were observed in the examined apple juices and apple juice extracts, depending on conditions of production and the apple varieties used. Considering clear and cloudy juices of one batch, procyanidin content and their mean degree of polymerisation were reduced significantly by the process of clarification. Furthermore, higher contents and higher mean degrees of polymerisation were found in juices deriving from one cider apple variety than in juices blended with dessert apples. (R)-Octane-1,3-diol, (R)-5-(Z)-octene-1,3-diol, 3-hydroxy-2-pyrone and 3-hydroxy-β-damascone were non-phenolic ingredients of the examined apple juices and apple juice extracts. Two selected apple juice extracts produced in 2004 and 2006 were fractionated using different preparative chromatographic methods. In the course of preparative fractionations, the substances quercetin, quercetin 3-O-glucoside, quercetin 3-O-galactoside, phloretin 2’-xyloglucoside, 3-hydroxyphloretin 2’-glucoside, 3-hydroxyphloretin 2’-xyloglucoside, und phloretin 2’,4’-diglucoside were obtained. Obtained subfractions and pure substances were tested in vitro for their inhibitory potentials with respect to protein tyrosine kinase (PTK) at the epidermal growth factor receptor (EGFR). In cancer cells this receptor is overexpressed and contributes to unregulated growth. Furthermore, antioxidative (DPPH, ORAC, X/XO), antiinflammatory and antihormonal (COX-1, CYP19) properties as well as the ability to modulate enzymes of xenobiotic metabolism (CYP1A, QR) were investigated. Apple procyanidins showed, depending on their degree of polymerisation, strong inhibition of the PTK at the EGFR. So fractions containing exclusively high-polymeric procyanidins (NP.4 and NP.5) showed a clearly stronger inhibition than fractions containing only low-molecular polyphenols. Procyanidines also had a decisive impact on the enzymes cytochrom P450 1A and aromatase (CYP19). Antioxidative properties of apple juice extracts were dependent on the content of both, polymeric procyanidins and low-molecular polyphenols. On the one hand both phenolic groups contributed to the radical scavenging properties and to an inhibition of superoxide anion generation, attested to the examined apple juice extracts. On the other hand, peroxyl radicals generated during the ORAC assay were only quenched by low molecular compounds. The inhibitory potential of the isolated 3-hydroxyphloretin (glycosides) with respect to the protein tyrosine kinase of the epidermal growth receptor was greater than of their corresponding phloretin (glycosides), except for the xyloglucoside. Inconsistent results were obtained from investigations of xenobiotic metabolising enzymes. So, phloretin was a more effective inhibitor of CYP1A than 3-hydroxphloretin, whereas, regarding the glycosides, 3-hydroxyphloretin glycosides were more effective. Likewise, 3-hydroxyphloretin (glycosides) exhibited slightly better radical scavenging activities in the DPPH and X/XO assays than their non-hydroxylated analogs. Only the dihydroxylated free aglycon scavenged hydroxyl peroxide radicals more successfully. Furthermore, 3-hydroxy-beta-damascone was identified as a highly potent quinone reductase inductor from apple juice for the first time. Findings obtained in this work concerning newly identified bioactive compounds con-tribute to a better understanding of the potential chemopreventive effect of (cloudy) apple juices. Furthermore, quantification of these substances in apple juices, treated differently with respect to technological issues, is of relevance for further studies

THE REVOLUTION AHEAD: PUBLISH/SUBSCRIBE MEETS DATABASE SYSTEMS

The traditional way of user interaction with a database system follows the classical ’request/response ’ query paradigm where the user is issuing a query and retrieving the result as fast as possible. The primary issues are efficiency and consistency. Driven by huge numbers of concurrent users accessing large data sets especially in the context of Data Warehouse Systems, the ’request/response ’ paradigm looks no longer feasible. There is commonly no doubt that the novel query paradigm of ’publish/subscribe ’ may be one way to diminish the before mentioned problems. In the ’publish/subscribe ’ context, a user registers a subscription (also called a standing query) once at a subscription management system and periodically or aperiodically receives notifications, i.e. the result of the query with regard to the currently valid state of the underlying database. In this paper, we give an overview of the ’publish/subscribe ’ paradigm in general and introduce the framework of the content- and memory-based subscription system Pub-Scribe. The PubScribe framework provides an open platform for information publishing and registering of complex structured subscriptions. The PubScribe subscription model as well as the processing model are discussed. 1