Real-time transaction scheduling in database systems

A database system supporting a real-time application, which can be called "a real-time database system (RTDBS)", has to provide real-time information to the executing transactions. Each RTDB transaction is associated with a timing constraint, usually in the form of a deadline. Efficient resource scheduling algorithms and concurrency control protocols are required to schedule the transactions so as to satisfy both timing constraints and data consistency requirements. In this paper,† † An earlier version of this paper was published in the Proceedings of ACM Computer Science Conference '92. we concentrate on the concurrency control problem in RTDBSs. Our work has two basic goals: real-time performance evaluation of existing concurrency control approaches in RTDBSs, and proposing new concurrency control protocols with improved performance. One of the new protocols is locking-based, and it prevents the priority inversion problem‡ by scheduling the data lock requests based on prioritizing data items. The second new protocol extends the basic timestamp-ordering method by involving real-time priorities of transactions in the timestamp assignment procedure. Performance of the protocols is evaluated through simulations by using a detailed model of a single-site RTDBS. The relative performance of the protocols is examined as a function of transaction load, data contention (which is determined by a number of system parameters) and resource contention. The protocols are also tested under various real-time transaction processing environments. The performance of the proposed protocols appears to be good, especially under conditions of high transaction load and high data contention. © 1994

Real-time scheduling of transactions in multicore systems

International audienceTransactional memory has attracted much interest for multicore systems as it eases programming and avoids the problems of lock-based methods. However, introducing real-time scheduling of transactions in multicore systems is an open problem. Existing solutions for real-time scheduling consider either tasks in multiprocessor systems or transactions in database systems. In this paper, we show that these solutions are not suitable for multicore systems. And we discuss the main challenges to introduce real-time scheduling within transactional memory in multicore systems

A study of two transaction-processing architectures for distributed real-time database systems

Cataloged from PDF version of article.A real-time data base system (RTDBS) is designed to provide timely response to the transactions of data-intensive applications. Processing a transaction in a distributed RTDBS environment presents the design choice of how to provide access to remote data referenced by the transaction. Satisfaction of the timing constraints of transactions should be the primary factor to be considered in scheduling accesses to remote data. In this article, we describe and analyze two different alternative approaches to this fundamental design decision. With the first alternative, transaction operations are executed at the sites where required data pages reside. The other alternative is based on transmitting data pages wherever they are needed. Although the latter approach is characterized by large message volumes carrying data pages, it is shown in our experiments to perform better than the other approach under most of the work loads and system configurations tested. The performance metric used in the evaluations is the fraction of transactions that satisfy their timing constraints. © 1995

Analysis of concurrency control protocols for real-time database systems

Cataloged from PDF version of article.This paper provides an approximate analytic solution method for evaluating the performance of concurrency control protocols developed for real-time database systems (RTDBSs). Transactions processed in a RTDBS are associated with timing constraints typically in the form of deadlines. The primary consideration in developing a RTDBS concurrency control protocol is the fact that satisfaction of the timing constraints of transactions is as important as maintaining the consistency of the underlying database. The proposed solution method provides the evaluation of the performance of concurrency control protocols in terms of the satisfaction rate of timing constraints. As a case study, a RTDBS concurrency control protocol, called High Priority, is analyzed using the proposed method. The accuracy of the performance results obtained is ascertained via simulation. The solution method is also used to investigate the real-time performance benefits of the High Priority over the ordinary Two-Phase Locking. © 1998 Elsevier Science Inc. All rights reserved

A study of two transaction-processing architectures for distributed real-time data base systems

A real-time data base system (RTDBS) is designed to provide timely response to the transactions of data-intensive applications. Processing a transaction in a distributed RTDBS environment presents the design choice of how to provide access to remote data referenced by the transaction. Satisfaction of the timing constraints of transactions should be the primary factor to be considered in scheduling accesses to remote data. In this article, we describe and analyze two different alternative approaches to this fundamental design decision. With the first alternative, transaction operations are executed at the sites where required data pages reside. The other alternative is based on transmitting data pages wherever they are needed. Although the latter approach is characterized by large message volumes carrying data pages, it is shown in our experiments to perform better than the other approach under most of the work loads and system configurations tested. The performance metric used in the evaluations is the fraction of transactions that satisfy their timing constraints. © 1995

Research issues in real-time database systems. Survey paper

Today's real-time systems are characterized by managing large volumes of data. Efficient database management algorithms for accessing and manipulating data are required to satisfy timing constraints of supported applications. Real-time database systems involve a new research area investigating possible ways of applying database systems technology to real-time systems. Management of real-time information through a database system requires the integration of concepts from both real-time systems and database systems. Some new criteria need to be developed to involve timing constraints of real-time applications in many database systems design issues, such as transaction/query processing, data buffering, CPU, and IO scheduling. In this paper, a basic understanding of the issues in real-time database systems is provided and the research efforts in this area are introduced. Different approaches to various problems of real-time database systems are briefly described, and possible future research directions are discussed. © 1995

An evaluation of transaction management issues in mobile real-time database systems

Ankara : The Department of Computer Engineering and Information Science and Institute of Engineering and Science Bilkent University, 1998.Thesis (Master's) -- Bilkent University, 1998.Includes bibliographical references leaves 56-58.Kayan, ErsanM.S

Server application to process data from a MySQL database and their interpretation

Diplomová práca je o vytvorení serverovej aplikácie, ktorá spracuje a interpretuje dáta z databázy. Cieľom takejto aplikácie je dokázať spracovať veľký počet požiadavkou v reálnom čase. Poskytnutá databáza, s ktorou aplikácia pracuje obsahuje merania rýchlosti a kvality mobilného spojenia pomocou rádiových technológií ponúkaných jednotlivými mobilnými operátormi. Merania pochádzajú od užívateľov z celého sveta a množstvo meraní neustále rastie. Výsledkom práce je preto naprogramovaná serverová aplikácia, ktorá sa prispôsobuje narastajúcemu množstvu dát pomocou agregácie. Metóda agregácie a použitie indexov v tabuľkách databázy sú bližšie rozobrané v teoretickej časti diplomovej práce. Hlavne definícia indexov v databáze priniesla značné zrýchlenie spracovania databázových požiadaviek. Finálnym produktom diplomovej práce je aplikácia, ktorá sa skladá z troch komponentov: serverová aplikácia vykonávajúca agregáciu, webová stránka interpretujúca namerané dáta a back-end rozhranie taktiež poskytujúce namerané dáta. Webová stránka reprezentuje dáta vo forme grafov pre jednotlivé krajiny a rádiové technológie. Webová adresa prezentačnej stránky a návod na použitie sú poskytnuté v štvrtej kapitole diplomovej práce. Záverom sú uskutočnené testy rýchlosti odozvy vytvorenej aplikácie, ktoré potvrdzujú efektivitu vybraných a opísaných metód na zrýchlenie práce s databázou.Diploma thesis is about creating server application that process and interprets data from the database. Main aim of such application is able to process a large number of database requests in real-time environment. Provided database contains records of measuring download speed and quality of mobile connection via different radio technology from various providers. Those measured data are sent from users all around the world and amount of data collected is still growing. Therefore created server application can adapt to increasing size of database thanks to aggregation. This method of aggregation and use of index in database tables are further discussed in the theoretical part. Mainly putting indexes in tables produce significant acceleration of processing database requests. Final product of this thesis is an application that consist of three components: a server application running aggregation, website that interprets measured data and back-end interface providing measured data as well. Data at the website are presented in form of graphs for different countries and used radio technologies. Web address and user manual for finished applications are provided in the fourth chapter of diploma thesis. In the last part of thesis are performed various speed tests of programmed application that confirm the effectiveness of selected and described methods to accelerate work with the database.