abstract: This thesis addresses the problem of online schema updates where the goal is to be able to update relational database schemas without reducing the database system's availability. Unlike some other work in this area, this thesis presents an approach which is completely client-driven and does not require specialized database management systems (DBMS). Also, unlike other client-driven work, this approach provides support for a richer set of schema updates including vertical split (normalization), horizontal split, vertical and horizontal merge (union), difference and intersection. The update process automatically generates a runtime update client from a mapping between the old the new schemas. The solution has been validated by testing it on a relatively small database of around 300,000 records per table and less than 1 Gb, but with limited memory buffer size of 24 Mb. This thesis presents the study of the overhead of the update process as a function of the transaction rates and the batch size used to copy data from the old to the new schema. It shows that the overhead introduced is minimal for medium size applications and that the update can be achieved with no more than one minute of downtime. / Dissertation/Thesis / M.S. Computer Science 2011

Autonomous vehicle technology is advancing at a very high pace and self-driving trucks on control-tower operated work sites is already a reality. These autonomous trucks need a highly accurate map of the surroundings for operation and navigation, and it is of great importance to be able to update that map with the ever-changing off-road work site. The autonomous fleet examined have to stop for every update of the site map, which induces unnecessary downtime when updating the site map frequently. The purpose of this work is to contribute to the development of safe configurable maps for autonomous vehicles on off-road sites by identifying and analyzing different map updating methods, proposing the best one, and suggesting how to implement it for this project's case. The result was five different map updating methods, which were evaluated with respect to efficiency and safety. Efficiency was evaluated by comparing total fleet downtime of the proposed solutions with the existing situation. Safety was evaluated by doing a fault tree analysis (FTA) for each proposed solution and comparing the relative size of the fault trees. Proposed Solution III using map tiles was chosen as the most appropriate method to implement for this project's case because it is both efficient and relatively simple. It divides the site map with a grid into smaller rectangular maps and only needs to stop vehicles which are inside the updated tile. The rest of the fleet is able to replace that tile parallel to operation and, therefore, total fleet downtime is significantly reduced. By reaching the stated goal, this work is in line with its original purpose and has contributed to the development of safe configurable maps for autonomous vehicles on off-road sites.

Replication is a popular technique for increasing data availability and improving perfor- mance in peer-to-peer systems. Maintaining freshness of replicated data is challenging due to the high cost of update management. While updates have been studied in structured networks, they have been neglected in unstructured networks. We therefore confront the problem of maintaining fresh replicas of data in unstructured peer-to-peer networks. We propose techniques that leverage path replication to support efficient lazy updates and provide freshness for cached data in these systems using only local knowledge. In addition, we show that locally available information may be used to provide additional guarantees of freshness at an acceptable cost to performance. Through performance simulations based on both synthetic and real-world workloads from big data environments, we demonstrate the effectiveness of our approach.

Replication is a popular technique for increasing data availability and improving perfor- mance in peer-to-peer systems. Maintaining freshness of replicated data is challenging due to the high cost of update management. While updates have been studied in structured networks, they have been neglected in unstructured networks. We therefore confront the problem of maintaining fresh replicas of data in unstructured peer-to-peer networks. We propose techniques that leverage path replication to support efficient lazy updates and provide freshness for cached data in these systems using only local knowledge. In addition, we show that locally available information may be used to provide additional guarantees of freshness at an acceptable cost to performance. Through performance simulations based on both synthetic and real-world workloads from big data environments, we demonstrate the effectiveness of our approach.

Yes / The web environment has been developing remarkably, and much work has been done towards improving web based notification systems, where servers act smartly by notifying and feeding clients with subscribed data. In this paper we have reviewed some of the problems with current solutions to real-time updates of multi user web applications; we introduce a new concept “adaptive polling” based on one AJAX technique “Polling” to reduce the high volume of redundant server connections with reasonable latency, we demonstrated a prototype implementation of the new concept which is then evaluated against the existing one; the positive results clearly indicated more efficiency in terms of client-server bandwidth.

The paper is titled: Phraseology updates in the contemporary Czech language The aim of this paper is to collect and describe phraseological updates. The collection of materials (resources) took place from January 2013 to June 2015. Updates were sought out from various sources - the media, books, the theater, the internet and landline calls. With the help of professional literature we first limited the theoretical framework of the issue and based on these theoretical attainments we classified the material according to the sources and types of resources from which it originated. In the summary of updates we can see for every idiom update its original version, its type of update, its specific description and its source with a comment specifying its occurrence etc. With the performed analysis we determined that the most common kinds of updates are contamination and lexical updates.

Knowledge representation and inference are the backbone of artificial intelligence, and logic programming is one of the most widely used knowledge representation tools. Logic programming with deduction/induction/abduction as the reasoning technique is serving numerous fields of artificial intelligence. In dynamic domains where there are constant changes in knowledge, updating the knowledge base is crucial to keep it stable. This thesis investigates the issues in updating the knowledge base. Two types of logic program based updates are considered, simple fact based updates where the knowledge base is updated by a simple fact, and rule based updates where the knowledge base is updated by a rule. A SLDNF based procedural approach is proposed to implement such updates. This thesis also investigates the issues involved in simple fact based and rule based abduction, and it is observed that updates are closely related to abduction. A SLDNF based procedural approach to perform simple fact/rule based updates and abduction is proposed as a result of this study / Master of Science (Hons)

Description Logics (DLs) form a family of knowledge representation formalisms which can be used to represent and reason with conceptual knowledge about a domain of interest. The knowledge represented by DLs is mainly static. In many applications, the domain knowledge is dynamic. This observation motivates the research on how to update the knowledge when changes in the application domain take place. This thesis is dedicated to the study of updating knowledge, more precisely, assertional knowledge represented in DLs. We explore whether the updated knowledge can be expressed in several standard DLs and, if so, whether it is computable and what is its size.

Description Logics (DLs) form a family of knowledge representation formalisms which can be used to represent and reason with conceptual knowledge about a domain of interest. The knowledge represented by DLs is mainly static. In many applications, the domain knowledge is dynamic. This observation motivates the research on how to update the knowledge when changes in the application domain take place. This thesis is dedicated to the study of updating knowledge, more precisely, assertional knowledge represented in DLs. We explore whether the updated knowledge can be expressed in several standard DLs and, if so, whether it is computable and what is its size.

Pendant la dernière décennie, le format de données XML est devenu l'un des principaux moyens de représentation et d'échange de données sur le Web. La détection de l'indépendance entre une requête et une mise à jour, qui a lieu en absence d'impact d'une mise à jour sur une requête, est un problème crucial pour la gestion efficace de tâches comme la maintenance des vues, le contrôle de concurrence et de sécurité. Cette thèse présente une nouvelle technique d'analyse statique pour détecter l'indépendance entre requête et mise à jour XML, dans le cas où les données sont typées par un schéma. La contribution de la thèse repose sur une notion de type plus riche que celle employée jusqu'ici dans la littérature. Au lieu de caractériser les éléments d'un document XML utiles ou touchés par une requête ou mise à jour en utilisant un ensemble d’étiquettes, ceux-ci sont caractérisés par un ensemble de chaînes d'étiquettes, correspondants aux chemins parcourus pendant l'évaluation de l’expression dans un document valide pour le schéma. L'analyse d'indépendance résulte du développement d'un système d'inférence de type pour les chaînes. Cette analyse précise soulève une question importante et difficile liés aux schémas récursifs: un ensemble infini de chaînes pouvant être inférées dans ce cas, est-il possible et comment se ramener à une analyse effective donc finie. Cette thèse présente donc une technique d'approximation correcte et complète assurant une analyse finie. L'analyse de cette technique a conduit à développer des algorithmes pour une implantation efficace de l'analyse, et de mener une large série de tests validant à la fois la qualité de l'approche et son efficacité. / In the last decade XML became one of the main standards for data storage and exchange on the Web. Detecting XML query-update independence is crucial to efficiently perform data management tasks, like those concerning view-maintenance, concurrency control, and security. This thesis presents a novel static analysis technique to detect XML query-update independence, in the presence of a schema. Rather than types, the presented system infers chains of types. Each chain represents a path that can be traversed on a valid document during query/update evaluation. The resulting independence analysis is precise, although it raises a challenging issue: recursive schemas may lead to infer infinitely many chains. This thesis presents a sound and complete approximation technique ensuring a finite analysis in any case, together with an efficient implementation performing the chain-based analysis in polynomial space and time.