Studies on a Distributed Database System in Personal Computer Network

本研究的主要目标是建立一种为数据库处理提供有效功能的操作系统的构建方法。这是因为传统操作系统上的数据库系统存在几个性能问题。在本财政年度，我们在由多台个人计算机通过局域网连接的实验系统上实现了一个原型系统，并对去年研究的软件分段和面向流的关系操作的性能进行了评估。此外，我们还研究了以下研究课题：1.事务处理中的异常处理；2.事务的重复执行；3.监控网络通信的服务器；4.基于表格形式的可视化用户界面；5.微型主机链接。在上述课题1中，我们研究了所有网络站点都由局域网连接的分布式环境中异常事件的处理方案，并为分布式异常处理开发了系统原语。在主题2和3中，我们研究了事务故障、站点故障和通信链路故障恢复的一般过程。在课题4和5中，我们实现了作为原型系统的网络协议的TCP/IP协议。在此基础上，利用Unix上的X-Window系统，在Unix工作站上实现了原型系统的部分用户界面，并验证了多个处理器之间分担用户界面任务的可能性。

The major objective in this research is to establish a construction method for the operating systems which provide effective functions for the database processing. This is because there are several performance problems of database systems on a conventional operating system. In this fiscal year, we have implemented a prototype system on the experimental system which consists of several personal computers connected by a local area network, and evaluated the performance of the software segmentation and stream-oriented relational operations which were studied in the last year. Furthermore, in this yoar, we have studied the following research subjects : 1. Exception handling in the tnansaction processing, 2. Duplicate executions of the transaction, 3. Server for monitoring network communications, 4. Visual user interface based on the tabular form, 5. Micro-mainframe link. In the above subject 1, we have studied the processing scheme of exceptional events in the distributed environment where all the network site are connnected by a local area network, and developed system primitives for the distributed exception handling. In the subjcet 2 and 3, we have studied a general procedure for the recovery from the failures of transaction, site, and communication link. In the subject 4 and 5, we have implemented the TCP/IP protocol as a network protocol of the prototype system. Furthermore, by using the X-window system on UNIX, we have implemented part of user interface of the prototype system on the UNIX workstation, and confirmed the possibility of sharing of the user interface task between several processors.