This book Databases and Transaction Processing constitutes a standard database textbook for advanced undergraduate and graduate courses— albeit with a somewhat different focus compared to the established books. As the subtitle An Application-Oriented Approach indicates, the authors put an emphasis on teaching the systematic usage of database systems—rather than concentrating on an in-depth coverage of implementation techniques for building database systems. The rationale for this focus is that many more students will be implementing applications than will actually be implementing database systems. Therefore, the authors set out to present the conceptual and engineering principles underlying the design and implementation of database and transaction processing applications. In order to provide a solid foundation for these principles, the book thoroughly presents the concepts and the theory underlying relational databases, conceptual/relational data modelling, and relational query languages. This book covers the material traditionally taught in an introductory course in database systems: the relational model, conceptual design, query languages (including SQL, QBE, relational algebra, and relational calculus), normalization theory, and query processing. In addition to these core database topics, the book also contains advanced database material often not covered in introductory texts and courses. Object databases, XML, and document processing on the web are given extensive coverage. Together with additional material on distributed databases, CORBA, OLAP, and data mining, the latter part of the book provides the basis for an advanced course on databases. The text also covers transaction processing in depth such that an entire course can be devised based on this book—maybe with some supplementary material from dedicated textbooks on this subject (e.g., Weikum and Vossen’s book which was reviewed by Marc Scholl in the preceding SIGMOD record). In addition to discussing issues related to building transactions and ACID properties, the book describes TP monitors, the architecture of centralized and distributed transaction processing systems, and the transactional issues related to building correct and efficient database applications.

Databases and Transaction Processing: An Application-Oriented Approach - Book Review.

A distributed storage system has MDSs (metadata servers). Directories of file system namespace are distributed to the MDSs based on hash value of inode number of each directory. Each directory is managed by a master MDS. When a directory grows with a file creation rate greater than a preset split threshold, the master MDS constructs a consistent hashing overlay with one or more slave MDSs and splits directory entries of the directory to the consistent hashing overlay based on hash values of file names under the directory. The number of MDSs in the consistent hashing overlay is calculated based on the file creation rate. When the directory continues growing with a file creation rate that is greater than the preset split threshold, the master MDS adds a slave MDS into the consistent hashing overlay and splits directory entries to the consistent hashing overlay based on hash values of file names.

Method for directory entries split and merge in distributed file system

This paper presents implementation strategies for building cloud-based IT environments for Korean central government agencies (K-Cloud Centers), to improve service delivery in the public sector and reduce the cost of government operations. This will be achieved by the introduction of cloud computing technologies in the data centers of the National Computing and Information Agency (NCIA). This paper also proposes an approach for building wide- area cloud-based IT centers for Korean local government autonomous entities (W-Cloud Centers), to enhance the efficiency of IT resource utilization via the consolidation of all IT resources operated by these local entities. Through the implementations of cloud computing in the public sector, the Korean government can realize a digital government capable of providing enhanced service environments, while reducing IT-related budgetary expenditures and protecting the environment.

Implementing Cloud Computing in the Current IT Environments of Korean Government Agencies

With the development of information technology, managers of enterprises pay attention to how to make decisions with a large scale of data stored in data warehouse. Data ware-house is an important component in Information Supply Chain. For an efficient infor-mation flow running through the Information Supply Chain, metadata and its management system guarantee the high quality of data sharing. In this paper, metadata and its manage-ment system are illustrated from several aspects. A framework and an implementation of metadata management system are proposed to give guidance for enterprises. Finally, the prospect of application on metadata management is concluded.

Design and application on metadata management for information supply chain

A first memory stores requester event records describing events that occurred in relation to processes executed in a first server. A second memory stores requestee event records describing events that occurred in relation to processes executed in a second server in response to execution requests issued from the first server. An associating unit searches the first and second memories for requester event records and requestee event records whose transaction identifiers are identical and associates the found records together. A determining unit compares the associated event records with each other in terms of their time information. Based on this comparison, the determining unit determines a correction value for correcting time differences between requester event records in the first memory and requestee event records in the second memory.

Information processing apparatus and method for determining time correction values

This paper presents an effective method of metadata rebalance in exascale distributed file systems. Exponential data growth has led to the need for an adaptive and robust distributed file system whose typical architecture is composed of a large cluster of metadata servers and data servers. Though each metadata server can have an equally divided subset from the entire metadata set at first, there will eventually be a global imbalance in the placement of metadata among metadata servers, and this imbalance worsens over time. To ensure that disproportionate metadata placement will not have a negative effect on the intrinsic performance of a metadata server cluster, it is necessary to recover the balanced performance of the cluster periodically. However, this cannot be easily done because rebalancing seriously hampers the normal operation of a file system. This situation continues to get worse with both an ever-present heavy workload on the file system and frequent failures of server components at exascale. As one of the primary reasons for such a degraded performance, file system clients frequently fail to look up metadata from the metadata server cluster during the period of metadata rebalance; thus, metadata operations cannot proceed at their normal speed. We propose a metadata rebalance model that minimizes failures of metadata operations during the metadata rebalance period and validate the proposed model through a cost analysis. The analysis results demonstrate that our model supports the feasibility of online metadata rebalance without the normal operation obstruction and increases the chances of maintaining balance in a huge cluster of metadata servers.

Adaptive metadata rebalance in exascale file system

Provided is a system and method for updating a plurality of the same files consistently. The file update system comprises a first and a second data servers formed as pipe line type network for storing an original file and a duplicate file of the original file respectively, and for updating both the original file and the duplicate file in response to an update request, wherein the first and the second data servers mutually exchange file update information, correct the file update information so as to prevent overlapped update due to a plurality of update requests for the same file, and then update the original file or the duplicate file according to the corrected file update information.

System and method for updating file

Provided are an apparatus and a method for acquiring a consistent result even if one client accesses any metadata server in a circumstance that the cluster configuring many metadata servers exist. The apparatus as mentioned above includes a deletion file list unit that stores information about a deleted metadata during a predetermined period; and a metadata server selector that selects a metadata server to receive a operation request about a metadata among a plurality of metadata servers based on information from the deletion file list unit.

Apparatus and method for accessing a metadata

The need for saving a great many files becomes necessary in distributed file system environment. Particularly, some file systems maintain multiple file replicas for efficient failure recovery. Under these circumstances, however, all the file replicas have to be modified identically to update a file. If there are many clients to update the same file concurrently, the final images of all replicas can be inconsistent. In this paper, we propose a consistent update method so that a file can have the identical image in all replicas after concurrent modifications by multiple clients.

Design and Implementation of a Consistent Update Method for Multiple File Replicas in a Distributed File System

According to the development of the object based storage device (OSD) and networking technologies, some OSD based clustering file systems, for example, the ActiveScale storage cluster of the Panasas Corp. and the Lustre file system of the Cluster File System Corp., are emerging in the marketplace. Typically, these systems connect multiple OSDs on the fast network. When a large number of OSDs are connected as a linear style configuration, a client machine stores a file in its local memory first and then flushes it into an OSD. However, the file stored temporarily in the client's memory may not be completely stored in the selected OSD because the size of the file can be bigger than that of the OSD's available space. In this paper, we propose a detailed algorithm and system structure for solving this problem occurring in the cluster file system using OSDs.

Myung-Hoon Cha

Papers

Adaptive metadata rebalance in exascale file system

System and method for updating file

Apparatus and method for accessing a metadata

Design and Implementation of a Consistent Update Method for Multiple File Replicas in a Distributed File System

Design and Implementation of a File Spanning among Multiple OSDs in OASIS File System