Dynamic Data Allocation in Model Computing

移动的计算机，如掌上电脑、笔记本电脑和个人通信系统的用户不久将可以通过无线网络在线访问大量数据库。 据估计，这一活动的潜在市场每年在接入和通信费用方面达数十亿美元。 例如，在旅途中，乘客将访问航空公司和其他航空公司的时间表以及天气信息。 投资者将访问金融工具的价格，销售人员将访问库存数据，呼叫者将访问交通信息，无处不在的可穿戴计算机将访问各种数据库。 无线通信比有线通信更昂贵且更不可靠。 我们证明了在线数据的分配/复制方式在移动的计算机影响，成本和数据的可用性，因此数据分配必须根据不断变化的条件，如访问模式，用户的位置等。 目前，分布式数据库的分配方案是在设计数据库时以静态方式建立的。 分配方案保持固定，直到设计人员手动干预以更改副本的数量或其位置。 我们表明，这是一个不满意的解决方案，特别是在移动的计算。

Users of mobile computers, such as palmtops, notebook computers and personal communications systems, will soon have online access to a large number of databases via wireless networks. The potential market for this activity is estimated to be billion of dollars annually, in access and communication charge. For example, while on the road, passengers will access airline and other carriers schedules, and weather information. Investors will access prices of financial instruments, salespeople will access inventory data, callers will access traffic information, and wearable ubiquitous computers will access a wide variety of databases. Wireless communication is more expensive and less reliable that wire communication. We demonstrate that the way online data is allocated/replicated at mobile computers affect both, cost and data availability, and therefore data allocations has to change according to changing conditions, such as access patterns, users' location, etc. Presently, the allocation scheme of a distributed database is established in a static fashion, when the database is designed. The allocation scheme remains fixed until the designer manually intervenes to change the number of replicas or their location. We show that this is an unsatisfactory solution, particularly in mobile computing.