Apesar das vantagens das funcionalidades de banco de dados temporais, já amplamente demonstradas na literatura, ainda não existe, comercialmente, um SGBD totalmente temporal. Algumas propostas já foram feitas, embora um pouco discretas, dando ênfase em apenas parte das funcionalidades temporais, já sinalizando que em breve será possível existir um SGBD puramente temporal. Uma dessas propostas se constitui na implementação de uma camada de software que simula um banco de dados temporal, chamada Pacote de Tempo de Validade – PTV. Ela foi desenvolvida para demonstrar algumas funções temporais de banco de dados de tempo de validade. Embora o PTV tenha funções para garantir a integridade de dados temporais na inserção de tuplas, além de outros controles, não apresenta funções de consultas temporais. Essas funções foram desenvolvidas neste trabalho com base no TSQL2, aumentando, portanto, as funcionalidades temporais do PTV. Elas foram desenvolvidas para o SGBD Oracle 9i e consistem da principal proposta desse trabalho, permitindo inclusive validar as funções de consultas temporais de outras propostas da literatura. A segunda proposta desse trabalho é prover aos desenvolvedores e pesquisadores dessa área, uma interface visual apropriada para o uso do PTV, permitindo, assim, a exploração máxima dos recursos temporais desse pacote.

Embora há muito tempo já se tenha conhecimento da importância da recuperação de informações temporais, não existe um SGBD temporal que tenha sido desenvolvido unicamente para aplicações comerciais, que supra todas as necessidades e abranja todos os aspectos temporais necessários a estas aplicações. O SGBD da Oracle, a partir da versão 8i, possibilita a inserção de características temporais similares às de tempo de transação no BD, através de um pacote de tempo denominado Time Series Cartridge. Entretanto, em muitos casos, a utilização deste cartucho de tempo não é suficiente para que se possa implementar por completo tudo o que foi especificado na modelagem do sistema. A modelagem completa da realidade só é alcançada se forem utilizadas em conjunto as características de tempo de transação e de tempo de validade no banco de dados. Neste trabalho são sugeridos e implementados mecanismos para a inserção e o gerenciamento do tempo de validade no SGBD Oracle. O tempo de validade é administrado através da execução de funções, procedimentos, gatilhos e objetos, organizados em forma de um pacote, de maneira que este possa ser utilizado em conjunto com o Time Series Cartridge.

M.Sc. (Informatics) / Please refer to full text to view abstract

Prof. S.H. von Solms

The goal of this thesis is to evaluate the implementation of new information system in a selected corporation. Minor goal is to evaluate the outsourcing solutions related to the information system in the same company. The thesis includes detailed description of the impact of implementation and the current state of business taking into consideration the information system and its limits. Additional insights are provided by explaining the relationship between the corporation and the outsourcing companies chosen. This is evaluated and with the support of internal expertise and statistics, is concluded, that the implementation was successful. Added value of this thesis is an insight in the process of implementation of a complex information system in a worldwide corporation.

Increased production and use of multimedia data has led to the development of a more advanced Database Management System (DBMS), like an Object Relational Database Management System (ORDBMS). These advanced databases are necessitated by the complexity in structure and the functionality required by multimedia data. Unfortunately, no suitable benchmarks exist with which to test the performance of databases when handling multimedia data. This thesis describes the design of a benchmark to measure the performance of basic functionality found in multimedia databases. The benchmark, called MORD (Multimedia Object Relational Databases), targets Oracle, a well known commercial Object Relational Database Management System (ORDBMS) that can handle multimedia data. Although MORD targets Oracle, it can easily be applied to other Multimedia Database Management System (MMDBMS) as a result of a design that stressed its portability, and simplicity. MORD consists of a database schema, test data, and code to simulate representative queries on multimedia databases. A number of experiments are described that validate MORD and ensure its correct design and that its objectives are met. A by-product of these experiments is an initial understanding of the performance of multimedia databases. The experiments show that with multimedia data the buffer cache should be at least large enough to hold the largest dataset, a bigger block size improves the performance, and turning off logging and caching for bulk loading improves the performance. MORD can be used to compare different ORDBMS or to assist in the configuration of a specific database.

Diplomová práce se zaměřuje na propojení databáze Oracle s vývojovými platformami Java, .Net a Lotus Notes/Domino. Po vysvětlení základních principů a technik práce s databází následuje část, která si klade za cíl jednotlivé možnosti propojení porovnat a otestovat. Na všech 3 platformách existují vyspělé propojovací technologie pro práci s databází, mezi nejznámější patří ODBC, JDBC, ADO.NET a LC (Lotus Connectors). Jednotlivé možnosti propojení se na všech třech vývojových platformách značně liší. Společná zůstává jen základní funkcionalita pro práci s databází (sestavení připojení, řízení transakcí, volání SQL příkazů, přenášení základních datových typů a volání uložených procedur). Pro praktické ověření jednotlivých propojovacích produktů byla vyvinuta testovací/benchmark aplikace, která byla z jazyka Java naimplementována i do prostředí .NET (C#) a Lotus Notes/Domino (Lotus Script). Bylo naimplementováno a spuštěno 253 testů na 12 produktech od 8 výrobců. Podkladem pro zpracování diplomové práce a realizaci testů byla dokumentace k těmto systémům a další odborná literatura. Díky těmto testům bylo možné, v rámci možností, porovnání jednotlivých produktů i platforem. Systematické testování a práce s těmito produkty ukázaly, že jednotlivé produkty jsou velmi rozdílné v ceně, kvalitě, výkonu, ale i ve svých specifických funkcích.

Thesis deal with tuning of database Oracle, which is used by digital archive SAFE. In the concrete deal with setting parameters of database. It is divided to three parts. In first part it characterizes factors that influence performance of database. In second part it describes possibilities of tuning and setting Oracle database. In third part it is first introduced digital archive SAFE, after that it is chosen suitable testing tool for workload generation and described test scenarios and last are performed tests and compared results at different database database settings. Goal of thesis is description and trial tuning of Oracle database, which is used by digital archive SAFE. Other goal is test of files inserting into digital archive at different settings (saving to the database, on file system). These goals are achieved by testing tool workload generation and compare response time at different settings. Contribution of this thesis is above all trial of tuning Oracle database, which is used by digital archive SAFE. Document can be used like handbook for implementatory of tested implementation of digital archive SAFE.

We investigate so-called partitioning oracle attacks against AES-GCM and ChaCha20-Poly1305 along with some improvements. Such attacks against these two cryptosystems are efficient because they can be reduced to solving linear systems of equations over finite fields. We show, with some randomness assumptions, that such linear systems must have at least as many columns as rows. We have also chosen two finite (non-field) rings, as replacement for the respective fields used by AES-GCM and ChaCha20-Poly1305 for message authentication. These rings make the problem of linear system arrangement in a partitioning oracle attack extremely hard for large linear system dimensions.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24388号 / 理博第4887号 / 新制||理||1699(附属図書館) / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 牧野 和久, 教授 並河 良典, 教授 長谷川 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM