• Title/Summary/Keyword: main-memory database system

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A Study of Performance Decision Factor for Moving Object Database in Main Memory Index (이동체 데이터베이스를 위한 메인 메모리 색인의 성능 결정 요소에 관한 연구)

  • Lee, Chang-Woo;Ahn, Kyoung-Hwan;Hong, Bong-Hee
    • Proceedings of the Korea Information Processing Society Conference
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    • 2003.05c
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    • pp.1575-1578
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    • 2003
  • 이동통신 기술의 발달로 인하여 무선 이동 기기의 사용이 보편화되면서 LBS(Location Based System)의 요구가 나날이 증대되고 있다. 이와 같은 위치 기반 서비스에서 클라이언트인 이동체들은 일정한 보고 주기를 가지고 서버에 위치 데이터를 보고하게 되는데, 빈번한 보고 데이터를 실시간으로 처리하기 위해서 서버에서는 메인 메모리 DBMS를 유지하는 것이 필요하다. 기존에 제시된 메인 메모리 색인으로는 T-tree 가 있는데, 이는 1차원 데이터를 위한 것이므로 이동체 데이터베이스 환경에 적합하지 못하다. 그리고, 디스크 기반의 다차원 색인으로는 R-tree 계열이 있는데, 이는 메인 메모리에서 효율적인 사용을 보장하지 못한다. 이 논문에서는 이동체 데이터베이스 환경에 적합한 메인 메모리 색인을 고려함에 있어서, 기존의 디스크 기반의 다차원 색인으로 가장 널리 알려진 R-tree 계열의 색인을 메인 메모리에 적재 후 메인 메모리 환경에서 성능에 영향을 주는 요소를 실험을 통하여 제시한다. 실험은 메인 메모리에서는 간단한 알고리즘을 사용하는 것이 성능에 좋고, 삽입 시에는 삽입할 노드를 찾기 위해서 비교하는 엔트리의 수가, 검색 시에는 노드간의 중첩으로 인하여 비교하는 노드의 수와 엔트리의 수가 성능에 영향을 주는 요소임을 보여준다.

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An Attribute Replicating Vertical Partition Method by Genetic Algorithm in the Physical Design of Relational Database (관계형 데이터베이스의 물리적 설계에서 유전해법을 이용한 속성 중복 수직분할 방법)

  • 유종찬;김재련
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.21 no.46
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    • pp.33-49
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    • 1998
  • In order to improve the performance of relational databases, one has to reduce the number of disk accesses necessary to transfer data from disk to main memory. The paper proposes to reduce the number of disk I/O accesses by vertically partitioning relation into fragments and allowing attribute replication to fragments if necessary. When zero-one integer programming model is solved by the branch-and-bound method, it requires much computing time to solve a large sized problem. Therefore, heuristic solutions using genetic algorithm(GA) are presented. GA in this paper adapts a few ideas which are different from traditional genetic algorithms, for examples, a rank-based sharing fitness function, elitism and so on. In order to improve performance of GA, a set of optimal parameter levels is determined by the experiment and makes use of it. As relations are vertically partitioned allowing attribute replications and saved in disk, an attribute replicating vertical partition method by GA can attain less access cost than non-attribute-replication one and require less computing time than the branch-and-bound method in large-sized problems. Also, it can acquire a good solution similar to the optimum solution in small-sized problem.

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Human Laughter Generation using Hybrid Generative Models

  • Mansouri, Nadia;Lachiri, Zied
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.15 no.5
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    • pp.1590-1609
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    • 2021
  • Laughter is one of the most important nonverbal sound that human generates. It is a means for expressing his emotions. The acoustic and contextual features of this specific sound are different from those of speech and many difficulties arise during their modeling process. During this work, we propose an audio laughter generation system based on unsupervised generative models: the autoencoder (AE) and its variants. This procedure is the association of three main sub-process, (1) the analysis which consist of extracting the log magnitude spectrogram from the laughter database, (2) the generative models training, (3) the synthesis stage which incorporate the involvement of an intermediate mechanism: the vocoder. To improve the synthesis quality, we suggest two hybrid models (LSTM-VAE, GRU-VAE and CNN-VAE) that combine the representation learning capacity of variational autoencoder (VAE) with the temporal modelling ability of a long short-term memory RNN (LSTM) and the CNN ability to learn invariant features. To figure out the performance of our proposed audio laughter generation process, objective evaluation (RMSE) and a perceptual audio quality test (listening test) were conducted. According to these evaluation metrics, we can show that the GRU-VAE outperforms the other VAE models.

An Effective Method Guaranteeing Mutual Exclusion of Lock Waiting Information for Deadlock Detection in Main Memory Databases (주기억장치 데이타베이스에서 교착 상태의 검출을 위한 락 대기 정보의 효과적인 상호 배제 기법)

  • Kim, Sang-Wook;Lee, Seung-Sun;Choi, Wan
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.7B
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    • pp.1313-1321
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    • 1999
  • The two-phase locking protocol(2PL) is the most widely-used concurrency control mechanism for guaranteeing logical consistency of data in a database environment where a number of transactions perform concurrently. The problem inherent in the 2PL protocol is a deadlock, where a set of transactions holding some locks indefinitely wait an additional lock that is already held by other transactions in the set. The deadlock detector is a DBMS sub-component that examines periodically whether a system is in a deadlock state based on lock waiting information of transactions. The deadlock detector and transactions execute concurrently in a DBMS and read and/or write the lock waiting information simultaneously. Since the lock waiting information is a shared one, we need an efficient method guaranteeing its physical consistency by using mutual exclusion. The efficiency of the mutual exclusion method is crucial especially in a main memory DBMS with high performance since it seriously affects the performance of an entire system. In this paper, we propose a new method that effectively guarantees physical consistency of lock waiting information. Two primary goals of our method are to minimize the processing overhead and to maximize system concurrency.

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Design and Implementation of Query Classification Component in Multi-Level DBMS for Location Based Service (위치기반 서비스를 위한 다중레벨 DBMS에 질의 분류 컴포넌트의 설계 및 구현)

  • Jang Seok-Kyu;Eo Sang Hun;Kim Myung-Heun;Bae Hae-Young
    • The KIPS Transactions:PartD
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    • v.12D no.5 s.101
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    • pp.689-698
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    • 2005
  • Various systems are used to provide the location based services. But, the existing systems have some problems which have difficulties in dealing with faster services for above million people. In order to solve it, a multi-level DBMS which supports both fast data processing and large data management support should be used. The multi-level DBMS with snapshots has all the data existing in disk database and the data which are required to be processed for fast processing are managed in main memory database as snapshots. To optimize performance of this system for location based services, the query classification component which classifies the queries for efficient snapshot usage is needed. In this paper, the query classification component in multi-level DBMS for location based services is designed and implemented. The proposed component classifies queries into three types: (1) memory query, (2) disk query, (3) hybrid query, and increases the rate of snapshot usage. In addition, it applies division mechanisms which divide aspatial and spatial filter condition for partial snapshot usage. Hence, the proposed component enhances system performance by maximizing the usage of snapshot as a result of the efficient query classification.

Transaction Scheduling Technique Using Doible Locking in a Soft Real-Time Databaes System (소프트 실시간 데이타베이스 시스템에서 이중 록킹을 이용한 트랜잭션 스케쥴링 기법)

  • Choi, Eui-In;Go, Byeong-O
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.3
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    • pp.639-648
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    • 1997
  • As the areas of computer application are expanded, the real-time applicition enviroments that must process as many transactions as possible within their deadlines have been increased recently. Conventional disk based databaes system is not appropriate in real-time transaction processing due to delying time for disk I/O processing. When the system is overloaede, the performance of transaction scheduling technique using earliest deadline first deteriorates rapidly because it can assign the highest priority ot a transaction that has already missed or is about to miss tis deadline. Therfore, the performance of suggested transaction secheduling technique is made to improved by propos-ing the doule locking mechanism based on priority. Finally, in order to evaluate the performance of the proposed priority-based double locking techniques under single proessor and main memory database system environments, the simulation model was developed using the SLAM II language.

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Design and Implementation of High-dimensional Index Structure for the support of Concurrency Control (필터링에 기반한 고차원 색인구조의 동시성 제어기법의 설계 및 구현)

  • Lee, Yong-Ju;Chang, Jae-Woo;Kim, Hang-Young;Kim, Myung-Joon
    • The KIPS Transactions:PartD
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    • v.10D no.1
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    • pp.1-12
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    • 2003
  • Recently, there have been many indexing schemes for multimedia data such as image, video data. But recent database applications, for example data mining and multimedia database, are required to support multi-user environment. In order for indexing schemes to be useful in multi-user environment, a concurrency control algorithm is required to handle it. So we propose a concurrency control algorithm that can be applied to CBF (cell-based filtering method), which uses the signature of the cell for alleviating the dimensional curse problem. In addition, we extend the SHORE storage system of Wisconsin university in order to handle high-dimensional data. This extended SHORE storage system provides conventional storage manager functions, guarantees the integrity of high-dimensional data and is flexible to the large scale of feature vectors for preventing the usage of large main memory. Finally, we implement the web-based image retrieval system by using the extended SHORE storage system. The key feature of this system is platform-independent access to the high-dimensional data as well as functionality of efficient content-based queries. Lastly. We evaluate an average response time of point query, range query and k-nearest query in terms of the number of threads.

A Recommendation System of Exponentially Weighted Collaborative Filtering for Products in Electronic Commerce (지수적 가중치를 적용한 협력적 상품추천시스템)

  • Lee, Gyeong-Hui;Han, Jeong-Hye;Im, Chun-Seong
    • The KIPS Transactions:PartB
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    • v.8B no.6
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    • pp.625-632
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    • 2001
  • The electronic stores have realized that they need to understand their customers and to quickly response their wants and needs. To be successful in increasingly competitive Internet marketplace, recommender systems are adapting data mining techniques. One of most successful recommender technologies is collaborative filtering (CF) algorithm which recommends products to a target customer based on the information of other customers and employ statistical techniques to find a set of customers known as neighbors. However, the application of the systems, however, is not very suitable for seasonal products which are sensitive to time or season such as refrigerator or seasonal clothes. In this paper, we propose a new adjusted item-based recommendation generation algorithms called the exponentially weighted collaborative filtering recommendation (EWCFR) one that computes item-item similarities regarding seasonal products. Finally, we suggest the recommendation system with relatively high quality computing time on main memory database (MMDB) in XML since the collaborative filtering systems are needed that can quickly produce high quality recommendations with very large-scale problems.

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Development of the Information Delivery System for the Home Nursing Service (가정간호사업 운용을 위한 정보전달체계 개발 I (가정간호 데이터베이스 구축과 뇌졸중 환자의 가정간호 전산개발))

  • Park, J.H;Kim, M.J;Hong, K.J;Han, K.J;Park, S.A;Yung, S.N;Lee, I.S;Joh, H.;Bang, K.S
    • Journal of Home Health Care Nursing
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    • v.4
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    • pp.5-22
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    • 1997
  • The purpose of the study was to development an information delivery system for the home nursing service, to demonstrate and to evaluate the efficiency of it. The period of research conduct was from September 1996 to August 31, 1997. At the 1st stage to achieve the purpose, Firstly Assessment tool for the patients with cerebral vascular disease who have the first priority of HNS among the patients with various health problems at home was developed through literature review. Secondly, after identification of patient nursing problem by the home care nurse with the assessment tool, the patient's classification system developed by Park (1988) that was 128 nursing activities under 6 categories was used to identify the home care nurse's activities of the patient with CAV at home. The research team had several workshops with 5 clinical nurse experts to refine it. At last 110 nursing activities under 11 categories for the patients with CVA were derived. At the second stage, algorithms were developed to connect 110 nursing activities with the patient nursing problems identified by assessment tool. The computerizing process of the algorithms is as follows: These algorithms are realized with the computer program by use of the software engineering technique. The development is made by the prototyping method, which is the requirement analysis of the software specifications. The basic features of the usability, compatibility, adaptability and maintainability are taken into consideration. Particular emphasis is given to the efficient construction of the database. To enhance the database efficiency and to establish the structural cohesion, the data field is categorized with the weight of relevance to the particular disease. This approach permits the easy adaptability when numerous diseases are applied in the future. In paralleled with this, the expandability and maintainability is stressed through out the program development, which leads to the modular concept. However since the disease to be applied is increased in number as the project progress and since they are interrelated and coupled each other, the expand ability as well as maintainability should be considered with a big priority. Furthermore, since the system is to be synthesized with other medical systems in the future, these properties are very important. The prototype developed in this project is to be evaluated through the stage of system testing. There are various evaluation metrics such as cohesion, coupling and adaptability so on. But unfortunately, direct measurement of these metrics are very difficult, and accordingly, analytical and quantitative evaluations are almost impossible. Therefore, instead of the analytical evaluation, the experimental evaluation is to be applied through the test run by various users. This system testing will provide the viewpoint analysis of the user's level, and the detail and additional requirement specifications arising from user's real situation will be feedback into the system modeling. Also. the degree of freedom of the input and output will be improved, and the hardware limitation will be investigated. Upon the refining, the prototype system will be used as a design template. and will be used to develop the more extensive system. In detail. the relevant modules will be developed for the various diseases, and the module will be integrated by the macroscopic design process focusing on the inter modularity, generality of the database. and compatibility with other systems. The Home care Evaluation System is comprised of three main modules of : (1) General information on a patient, (2) General health status of a patient, and (3) Cerebrovascular disease patient. The general health status module has five sub modules of physical measurement, vitality, nursing, pharmaceutical description and emotional/cognition ability. The CVA patient module is divided into ten sub modules such as subjective sense, consciousness, memory and language pattern so on. The typical sub modules are described in appendix 3.

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Update Protocols for Web-Based GIS Applications (웹 기반 GIS 응용을 위한 변경 프로토콜)

  • An, Seong-U;Seo, Yeong-Deok;Kim, Jin-Deok;Hong, Bong-Hui
    • Journal of KIISE:Databases
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    • v.29 no.4
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    • pp.321-333
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    • 2002
  • As web-based services are becoming more and more popular, concurrent updates of spatial data should be possible in the web-based environments in order to use the various services. Web-based GIS applications are characterized by large quantity of data providing and these data should be continuously updated according to various user's requirements. Faced with such an enormous data providing system, it is inefficient for a server to do all of the works of updating spatial data requested by clients. Besides, the HTTP protocol used in the web environment is established under the assumption of 'Connectionless'and 'Stateless'. Lots of problems may occur if the scheme of transaction processing based on the LAN environment is directly applied to the web environment. Especially for long transactions of updating spatial data, it is very difficult to control the concurrency among clients and to keep the consistency of the server data. This paper proposes a solution of keeping consistency during updating directly spatial data in the client-side by resolving the Dormancy Region Lock problem caused by the 'Connectionless'and 'Stateless'feature of the HTTP protocol. The RX(Region-eXclusive) lock and the periodically sending of ALIVE_CLIENTi messages can solve this problem. The protocol designed here is verified as effective enough through implementing in the main memory spatial database system, called CyberMap.