Article
New Storage Devices and the Future of Database Management
At the beginning of the paper, it is demonstrated that the technology of the most widely used SQL-oriented database management systems (DBMS) is inextricably linked with the technology of hard disk drives with movable heads (HDD). Features of HDD affect the data structures and algorithms for performing operations, methods of managing the buffer pool of the DBMS, transaction management, query optimization, etc. At present, new types of data storage hardware have appeared: block solid-state drives (SSD) and storage-class memory (SCM). SSD characteristics made it expedient to develop a DBMS in terms of their exclusive use, but so far, no such DBMS has been created, and SSDs are used simply instead of HDDs in DBMSs that do not take into account their features. The availability of SCM enables radical simplification of the architecture of the database systems and significantly improve their performance. To do this, we need to rethink many of the ideas used in disk-based databases.
At the beginning of the paper, it is demonstrated that the technology of the most widely used SQL-oriented DBMS is inextricably linked with HDD technology. Features of HDD affect the data structures and algorithms for performing operations, methods of managing the buffer pool of the DBMS, transaction management, query optimization, etc. An alternative to a disk DBMS is an in-memory DBMS, storing databases entirely in the main memory. Despite the fact that in-memory DBMS has a number of advantages over disk DBMS, at present there is practically no competition. This, first of all, is due to natural limitations on the size of databases, inherent in in-memory DBMS. At present, new types of data storage hardware have appeared: SSD – block solid-state drives and SCM – storage-class memory (non-volatile main memory). SSD characteristics made it expedient to develop a DBMS in terms of their exclusive use, but so far such a DBMS has not been created, and SSDs are used simply instead of HDDs in DBMS that do not take into account their features. The availability of SCM allows to radically simplify the architecture of the database and significantly improve their performance. To do this, you need to review many of the ideas used in disk-based databases.
At the beginning of the paper, it is demonstrated that the technology of the most widely used SQL-oriented DBMS is inextricably linked with HDD technology. Features of HDD affect the data structures and algorithms for performing operations, methods of managing the buffer pool of the DBMS, transaction management, query optimization, etc. An alternative to a disk DBMS is an in-memory DBMS, storing databases entirely in the main memory. Despite the fact that in-memory DBMS has a number of advantages over disk DBMS, at present there is practically no competition. This, first of all, is due to natural limitations on the size of databases, inherent in in-memory DBMS. At present, new types of data storage hardware have appeared: SSD — block solid-state drives and SCM — storage-class memory (non-volatile main memory). SSD characteristics made it expedient to develop a DBMS in terms of their exclusive use, so far no such DBMS has been created, and SSDs are used simply instead of HDDs in DBMS that do not take their features into account. The availability of SCM allows one to radically simplify the architecture of the database and significantly improve their performance. To do this, you need to review many of the ideas used in disk-based databases.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traffic is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the final node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a finite-dimensional system of differential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of differential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.
Event logs collected by modern information and technical systems usually contain enough data for automated process models discovery. A variety of algorithms was developed for process models discovery, conformance checking, log to model alignment, comparison of process models, etc., nevertheless a quick analysis of ad-hoc selected parts of a journal still have not get a full-fledged implementation. This paper describes an ROLAP-based method of multidimensional event logs storage for process mining. The result of the analysis of the journal is visualized as directed graph representing the union of all possible event sequences, ranked by their occurrence probability. Our implementation allows the analyst to discover process models for sublogs defined by ad-hoc selection of criteria and value of occurrence probability
Existing approaches suggest that IT strategy should be a reflection of business strategy. However, actually organisations do not often follow business strategy even if it is formally declared. In these conditions, IT strategy can be viewed not as a plan, but as an organisational shared view on the role of information systems. This approach generally reflects only a top-down perspective of IT strategy. So, it can be supplemented by a strategic behaviour pattern (i.e., more or less standard response to a changes that is formed as result of previous experience) to implement bottom-up approach. Two components that can help to establish effective reaction regarding new initiatives in IT are proposed here: model of IT-related decision making, and efficiency measurement metric to estimate maturity of business processes and appropriate IT. Usage of proposed tools is demonstrated in practical cases.