基于ARM-Linux的SQLite嵌入式数据库技术

第一步,先对Linux下常见的数据库技术加以分析,接下来,对“嵌入式”系统开发的数据库需求之特点加以标注,论述“SQLite嵌入式”数据库之体系结构、开发技术.最后一步,结合“ARM Linux”开发平台,给出一些具体实现方式.     

基于SQLite的煤矿安全监控数据库研究

针对煤矿安全监控系统的需求、现场数据的重要性及现场数据在煤矿安全监控系统网关中存储的必要性,在综合考虑网关存储空间大小限制和嵌入式数据库是否易于使用等因素的基础上,分析了在煤矿安全监控系统网关中用嵌入式数据库存储现场数据的优点,实现了在基于ARM-LINUX架构的网关中应用嵌入式数据库SQLite存储现场采集的数据.     

基于SQLite数据库加密模块的设计与实现

在嵌入式系统的开发设计中,用数据库SQLite对系统的批量数据进行维护管理,可以大大提高程序的运行效率,但SQLite本身没有安全机制的支持.在分析电力系统应用需求,加密系统和SQLite的应用特点,体系结构和开发技术基础上,设计并实现加密模块.结果表明,SQLite增加加密功能后,安全性得以提高.     

嵌入式数据库SQLite上多版本并发控制的设计与实现

针对嵌入式数据库SQLite并发性能较低的问题,提出了一种基于多版本并发控制(MVCC)的并发控制设计.首先,设计了SQLite数据库的以提交的写事务为依据的版本划分方式,重新设计了数据记录的头部字段并以此划分了记录在不同版本访问下的可见性;然后,在SQLite原有结构基础上修改了增、删、查、改等操作与索引结构使得该数...     

A record linkage process of a cervical cancer screening database

This paper aims at to present the integration of the files of the Brazilian Cervical Cancer Information System (SISCOLO) in order to identify all women in the system. SISCOLO has the exam as the unit of observation and the women are not uniquely identified. It has two main tables: histology and cytology, containing the histological and cytological examinations of women, respectively. In this study, data from June 2006 to December 2009 were used. Each table was linked with itself and with the other through record linkage methods. The integration identified 6236 women in the histology table and 1,678,993 in the cytology table. 5324 women from the histology table had records in the cytology table. The sensitivities were above 90% and the specificities and precisions near 100%. This study showed that it is possible to integrate SISCOLO to produce indicators for the evaluation of the cervical cancer screening programme taking the woman as the unit of observation.     

The use of deleted tuples in database querying and updating

The traditional approach to database querying and updating treats insertions and deletions of tuples in an asymmetric manner: if a tuple is inserted then, intuitively, we think of as being true and we use this knowledge in query and update processing; in contrast, if a tuple is deleted then we think of as being false but we do not use this knowledge at all! In this paper, we present a new approach to database querying and updating in which insertions and deletions of tuples are treated in a symmetric manner. Contrary to the traditional approach, we use both inserted and deleted tuples in our derivation algorithms. Our approach works as follows: if the deletion of a tuple is requested, then we mark as being deleted without removing it from the database; if the insertion of a tuple is requested, then we simply place in the database and remove all its marked subtuples. Derivation of tuples is done using two derivation rules under one constraint: a tuple is derived only if has no marked subtuples in the database. The derivation rules reflect relational projection and relational join. The main contribution of our work is to provide a method which allows insertion or deletion of a tuple over any relation scheme in a deterministic way. Received: 12 June 1995 / 19 February 1997     

Improved deleted file recovery technique for Ext2/3 filesystem

Digital devices are increasingly being used in various crimes, and therefore, it becomes important for law enforcement agencies to be able to investigate and analyze digital devices. Accordingly, there is an increasing demand for digital forensic technologies which can recover the data concealed or deleted by criminals that are of prime importance. There are various digital forensic tools available for Windows-based systems and relatively a few of those for Linux-based systems. Thus, this paper suggests a deleted file recovery technique for the Ext 2/3 filesystem, which is commonly used in Linux. The research involved the analysis of the Ext filesystem structure, file storage structure, and metadata information of file. The shortcomings of the existing methods and methods implemented by the proposed technique to address them are presented. Further, a comparison of the performance of the proposed technique and that of the existing methods is presented.     

Detection and recovery techniques for database corruption

Increasingly, for extensibility and performance, special purpose application code is being integrated with database system code. Such application code has direct access to database system buffers, and as a result, the danger of data being corrupted due to inadvertent application writes is increased. Previously proposed hardware techniques to protect from corruption require system calls, and their performance depends on details of the hardware architecture. We investigate an alternative approach which uses codewords associated with regions of data to detect corruption and to prevent corrupted data from being used by subsequent transactions. We develop several such techniques which vary in the level of protection, space overhead, performance, and impact on concurrency. These techniques are implemented in the Dali main-memory storage manager, and the performance impact of each on normal processing is evaluated. Novel techniques are developed to recover when a transaction has read corrupted data caused by a bad write and gone on to write other data in the database. These techniques use limited and relatively low-cost logging of transaction reads to trace the corruption and may also prove useful when resolving problems caused by incorrect data entry and other logical errors.     

数据库中数据恢复的研究

随着数据库技术的广泛应用,数据库的安全也越来越受到重视.日志文件对数据库系统实现数据恢复十分必要,给出了一种日志模式并针对数据库系统可能发生的几种故障,并给出了相应的对策,以确保数据库的安全.     

A graph-spectral method for surface height recovery

This paper describes a graph-spectral method for 3D surface integration. The algorithm takes as its input a 2D field of surface normal estimates, delivered, for instance, by a shape-from-shading or shape-from-texture procedure. We commence by using the surface normals to obtain an affinity weight matrix whose elements are related to the surface curvature. The weight matrix is used to compute a row-normalized transition probability matrix, and we pose the recovery of the integration path as that of finding the steady-state random walk for the Markov chain defined by this matrix. The steady-state random walk is given by the leading eigenvector of the original affinity weight matrix. By threading the surface normals together along the path specified by the magnitude order of the components of the leading eigenvector we perform surface integration. The height increments along the path are simply related to the traversed path length and the slope of the local tangent plane. The method is evaluated on needle-maps delivered by a shape-from-shading algorithm applied to real-world data and also on synthetic data. The method is compared with the local geometric height reconstruction method of Bors, Hancock and Wilson, and the global methods of Horn and Brooks and Frankot and Chellappa.     

基于影子页面和混合日志的MMDB恢复方法

为了提升内存数据库从各种故障中恢复的速度,提出了基于影子页面技术、混合日志策略以及模糊检查点思想的内存数据库恢复方法。在分析内存数据库运行过程中主要的时间消耗点的基础上建立了内存数据库的系统模型,通过分析事务过程和检查点过程,讨论了该恢复策略的执行过程以及优点,讲述了内存数据库在此系统模型和恢复策略下的事务故障和系统故障的恢复过程以及系统的性能分析。     

一种新的关系数据库水印算法研究

针对现有水印算法的不足,提出了一种新的关系数据库水印算法.算法首先筛选出可以嵌入水印信息的属性并将他们划分为若干个等大的子集,然后将水印信息的每个二进制位嵌入到相应的子集中.水印检测依据的是中心极限定理,并且实现了水印信息的准确检测.最后通过SQL server进行仿真实验,验证此方法在现实应用中的有效性.     

基于孩子兄弟树的 FAT32 文件删除恢复算法

针对由主观或客观因素造成计算机中数据丢失的情况,提出一种Windows FAT32文件系统下基于孩子兄弟树的数据删除恢复算法。 介绍FAT32文件系统和孩子兄弟树,详细阐述了如何基于孩子兄弟树重建FAT32文件系统的目录树,快速搜索到被删除文件的目录项,并通过分析文件删除前后目录项中属性值的变化来恢复被删除的文件。     

A photometric sampling method for facial shape recovery

The authors propose a photometric method to recover facial shape that is consistent with expected facial proportions. The method borrows ideas from photometric sampling, a technique that estimates shape from continuous variations of a light source around a single circular path. This approach aims at enriching photometric information by including variations of the light source along its zenith angle. To this end, a luminance matrix describing lighting response along both azimuth and zenith angles of the light source is built for each pixel. A method based on fitting sine functions onto the singular vectors of the collected luminance matrices is proposed for estimating a surface normal map. The estimated surface normals are later refined to maximize a facial proportion criterion and finally be integrated. Experiments demonstrate that our approach successfully approximates 3D face shape while preserving facial proportions within the limits of expected depth.     

The metaphor machine: A database method for creativity support

This paper shows how a data base method can be applied to the automatic generation of metaphors. The utility of automatic metaphor generation is based on providing interactive support to creative human thinking processes. Such interactive support systems have been called Idea Processing systems, and are seen as special qualitative types of Decision Support Systems (DSS). They include functions to support metaphorical thinking as well as other modes of creative idea development. The paper presents brief backgrounds references on creativity and the relevance of metaphors, as well as to previous work in Idea Processing. It then presents a relational data base method for automatic metaphor generation. The method is described and illustrated, as well as shown in relational algebra and relational calculus notation. In conclusion, the paper indicates how the relational data base method presented can be operationalized through using existing data base software or by integration with a specialized interface for the particular application of metaphor generation.     

内存数据库的一种数据组织方式

近年来,电信和金融领域的主要应用已经变成数据密集型应用,数据库系统在其中扮演了关键的角色.但传统的基于磁盘的关系数据库系统却不能满足上述应用高性能、实时/近实时数据访问的要求,内存数据库系统则可以很好地满足各种应用系统的实时数据管理需求.介绍了内存数据库的一种内部数据组织方式,并对各种核心对象的存储及数据结构进行了分析.     

A Kalman filter updating method for the indoor moving object database

A moving object database (MODB), a database representing information on moving objects, has many uses in a wide range of applications, such as the digital battlefield and transportation systems. In the transportation system, an MODB processes queries such as “How long should I wait until the next bus arrives here?” Therefore, location information on moving objects reflects the most important data the MODB has to manipulate. Most moving objects are equipped with a GPS (Global Positioning System) unit that sends location information to the MODB. However, GPS signals are usually very weak inside enclosed structures; thus, locating indoor moving objects requires more than the GPS. In this regard, indoor positioning for location-based services (LBSs) has been an important research topic for the last decade. There are many other differences between indoor and outdoor MODBs. For examples, the area where the indoor moving objects are moving around is much smaller than where the outdoor moving objects are moving around, and the speed of indoor moving objects is much slower than that of outdoor ones. Therefore, the indoor moving object database (IMODB) should be studied separately from the outdoor MODB or the MODB.One of the most important problems that the MODB has to solve is the updating problem. In this regard, this paper proposes an updating method of IMODBs for location-based services. Our method applies the Kalman filter to the most recently collected series of measured positions to estimate the moving object’s position and velocity at the last moment of the series of the measurements and extrapolates the current position with the estimated position and velocity. If the difference between the extrapolated current position and the measured current position is less than the threshold, that is, if the two positions are close, we skip updating the IMODB.When the IMODB requires information on the moving object’s position at a certain moment T, it applies the Kalman filter to the series of the recorded measurements at the moments before T and extrapolates the position at T with the Kalman filter in the same manner as the updating process described earlier. To verify the efficiency of our updating method, we applied our method to a series of measured positions obtained by employing the fingerprinting indoor positioning method while we walked through the test bed. We then analyzed the test results to calculate savings of communication cost and error.     

A fault recovery method for optical means of data exchange

We propose a method to speed up detection, neutralization, and recovery of multiple faults in means of data exchange in controlling and measuring distributed structures that operate in the “floating master—slaves” mode. We use double optical ring channels for communication with an opposite direction of signal transmission. We use fast distributed computations in order to control the state of the means of data exchange.