<p>An active database management system can react to predefined events in the database, resulting in performing some appropriate action. ECA-rules are used to capture these predefined events and to express the appropriate action in the active database management system. An event is said to be an atomic occurrence and is either primitive or composite. D-SNOOP and O-SNOOP are two ways to describe the semantics of composite events. D-SNOOP is detection-based (an event is considered to be instantaneous) and O-SNOOP occurrence-based (an event is considered to occur over a time interval). Some problems concerning the detection of composite events using D-SNOOP semantics have been highlighted by Galton and Augusto (2001), who have created the O-SNOOP semantics to rectify some of the shortcomings of D-SNOOP. It is, however, not known what practical consequences O-SNOOP has on applications. To find some of these practical consequences, an advanced application that uses composite events must be used. In this work, the advanced application is a cooperative information system.</p><p>A cooperative information system is a system in which several agents work together to solve some common problem. The agents can take on a role as either manager (service requester) or agent (problem solver).</p><p>In this dissertation an investigation of the differences between O-SNOOP and D-SNOOP in applications handling cooperation protocols is presented. Our first objective has been to model a cooperation protocol using in turn the D-SNOOP and the O-SNOOP semantics. A further objective has been to compare the models of the cooperation protocols to identify any differences between using D-SNOOP and O-SNOOP semantics in applications handling cooperation protocols.</p>

<p>In a distributed database system, pessimistic concurrency control is often used to ensure consistency which implies that the execution time of a transaction is not predictable. The execution time of a transaction is not dependent on the local transactions only, but on every transaction in the system.</p><p>In real-time database systems it is important that transactions are predictable. One way to make transactions predictable is to use eventual consistency where transactions commit locally before they are propagated to other nodes in the system. It is then possible to get predictable transactions due to the fact that the execution time of the transaction only depends on concurrent transactions on the local node and not on delays on other nodes and delays from a network.</p><p>In this report an investigation is made on how a replication protocol using eventual consistency can be designed for, and implemented in, DeeDS, a distributed real-time database prototype. The protocol consists of three parts: a propagation method, a conflict detection algorithm, and a conflict resolution mechanism. The conflict detection algorithm is based on version vectors. The focus is on the propagation mechanism and the conflict detection algorithm of the replication protocol.</p><p>An implementation design of the replication protocol is made. A discussion on how the version vectors may be applied in terms of granularity (container, page, object or attribute) and how the log filter should be designed and implemented to suit the particular conflict detection algorithm is carried out. A number of test cases with focus on regression testing have been defined.</p><p>It is concluded that the feasibility of the conflict detection algorithm is dependent on the application type that uses DeeDS.</p>

An active database management system can react to predefined events in the database, resulting in performing some appropriate action. ECA-rules are used to capture these predefined events and to express the appropriate action in the active database management system. An event is said to be an atomic occurrence and is either primitive or composite. D-SNOOP and O-SNOOP are two ways to describe the semantics of composite events. D-SNOOP is detection-based (an event is considered to be instantaneous) and O-SNOOP occurrence-based (an event is considered to occur over a time interval). Some problems concerning the detection of composite events using D-SNOOP semantics have been highlighted by Galton and Augusto (2001), who have created the O-SNOOP semantics to rectify some of the shortcomings of D-SNOOP. It is, however, not known what practical consequences O-SNOOP has on applications. To find some of these practical consequences, an advanced application that uses composite events must be used. In this work, the advanced application is a cooperative information system. A cooperative information system is a system in which several agents work together to solve some common problem. The agents can take on a role as either manager (service requester) or agent (problem solver). In this dissertation an investigation of the differences between O-SNOOP and D-SNOOP in applications handling cooperation protocols is presented. Our first objective has been to model a cooperation protocol using in turn the D-SNOOP and the O-SNOOP semantics. A further objective has been to compare the models of the cooperation protocols to identify any differences between using D-SNOOP and O-SNOOP semantics in applications handling cooperation protocols.

In a distributed database system, pessimistic concurrency control is often used to ensure consistency which implies that the execution time of a transaction is not predictable. The execution time of a transaction is not dependent on the local transactions only, but on every transaction in the system. In real-time database systems it is important that transactions are predictable. One way to make transactions predictable is to use eventual consistency where transactions commit locally before they are propagated to other nodes in the system. It is then possible to get predictable transactions due to the fact that the execution time of the transaction only depends on concurrent transactions on the local node and not on delays on other nodes and delays from a network. In this report an investigation is made on how a replication protocol using eventual consistency can be designed for, and implemented in, DeeDS, a distributed real-time database prototype. The protocol consists of three parts: a propagation method, a conflict detection algorithm, and a conflict resolution mechanism. The conflict detection algorithm is based on version vectors. The focus is on the propagation mechanism and the conflict detection algorithm of the replication protocol. An implementation design of the replication protocol is made. A discussion on how the version vectors may be applied in terms of granularity (container, page, object or attribute) and how the log filter should be designed and implemented to suit the particular conflict detection algorithm is carried out. A number of test cases with focus on regression testing have been defined. It is concluded that the feasibility of the conflict detection algorithm is dependent on the application type that uses DeeDS.

Because of an interest in object-oriented database systems, designers have created systems to store and manipulate specific sets of abstract data types that belong to the real world environment they represent. Unfortunately, the advantage of these systems is also a disadvantage since no single object-oriented database system can be used for all applications. This paper describes an object-oriented database management system called the Object-oriented Database Editor (ODE) which overcomes this disadvantage by allowing designers to create and execute an object-oriented database that represents any type of environment and then to store it and simulate that environment. As conditions within the environment change, the designer can use ODE to alter that environment without loss of data. ODE provides a flexible environment for the user; it is efficient; and it can run on a personal computer.

The thesis deals with the complete design, development and implementation of the server solution and graphical user interface for an autonomous system for detecting risk situations at a railway crossing. The server solution consists of a server service and a database. The .NET Core platform was used to develop the server service and its purpose is to perform the collection, processing and storage of information about risky traffic situations recorded by the camera modules. The service uses a Cassandra cluster database for secure data storage, and the database schema was designed with a focus on high performance. The own user interface is implemented with a web application built on Razor Pages technology. This application presents recorded traffic incidents to the user, using its own REST API service as a data source. REST API implements all logical operations on the data in the database.

This master’s thesis solves design of information system in order to support process of test report realization. It describes life cycle from customer request to test results reporting. Here is also included list of all input and output requested parameters for each laboratory test.

Word embeddings are useful in many tasks in Natural Language Processing and Information Retrieval, such as text mining and classification, sentiment analysis, sentence completion, or dictionary construction. Word2vec and its predecessor fastText, both well-known models to produce word embeddings, are powerful techniques to study the syntactic and semantic relations between words by representing them in a low-dimensional vector. By applying algebraic operations on these vectors semantic relationships such as word analogies, gender-inflections, or geographical relationships can be easily recovered. The aim of this work is to investigate how word embeddings could be utilized to augment and enrich queries in DBMSs, e.g. to compare text values according to their semantic relation or to group rows according to the similarity of their text values. For this purpose, we use pre-trained word embedding models of large text corpora such as Wikipedia. By exploiting this external knowledge during query processing we are able to apply inductive reasoning on text values. Thereby, we reduce the demand for explicit knowledge in database systems. In the context of the IMDB database schema, this allows for example to query movies that are semantically close to genres such as historical fiction or road movie without maintaining this information. Another example query is sketched in Listing 1, that returns the top-3 nearest neighbors (NN) of each movie in IMDB. Given the movie “Godfather” as input this results in “Scarface”, “Goodfellas” and “Untouchables”.

Die stark wachsende Bedeutung der Analyse von Data Warehouse-Inhalten und bequemere Anfrageschnittstellen für Endbenutzer erhöhen das Aufkommen an OLAP-Queries signifikant. Bei der Reduktion des Arbeitsumfanges und dem Erreichen kurzer Antwortzeiten für diese komplexen Anfragen ist neben der Nutzung von Verarbeitungs- und I/O-Parallelität eine adäquate Datenallokation der Schlüssel zu guter Leistungsfähigkeit. Allerdings ist die Bestimmung einer geeigneten Fragmentierung und Allokation für große Datenmengen, wie sie z.B. in Form von Faktentabellen oder Indexstrukturen in relationalen Sternschemas vorliegen, ein schwieriges Problem. Hierfür existiert heutzutage praktisch keine Werkzeugunterstützung. Wir präsentieren daher einen Ansatz zur analytischen Bestimmung einer passenden multi-dimensionalen, hierarchischen Datenallokation. Unser Ansatz dürfte recht einfach in ein Werkzeug zur automatischen Unterstützung des Allokationsproblems integriert werden können.

Recommendations are crucial for the success of large websites. While there are many ways to de-termine recommendations, the relative quality of these recommenders depends on many factors and is largely unknown. We propose a new clas-sification of recommenders and comparatively evaluate their relative quality for a sample web-site. The evaluation is performed with AWESOME (Adaptive website recommenda-tions), a new data warehouse-based recommen-dation system capturing and evaluating user feedback on presented recommendations. More-over, we show how AWESOME performs an automatic and adaptive closed-loop website op-timization by dynamically selecting the most promising recommenders based on continuously measured recommendation feedback. We pro-pose and evaluate several alternatives for dy-namic recommender selection including a power-ful machine learning approach.