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Many applications today are being developed and deployed on multi-tier environments that involve browser-based clients, web application servers and backend databases. These applications need to generate web pages on-demand by talking to backend databases because of their dynamic nature, making middle-tier database caching an effective approach to achieve high scalability and performance.〔 In a three tier architecture, the application tier and data tier can be in different hosts. Throughput of the application is affected by the network speed. This network overhead will be avoided by having the database at the application tier. As commercial databases are heavy weight, it is not practically feasible to have the application and the database at the same host. There are lot of light-weight databases available on the market, which can be used to cache data from the commercial databases. == Benefits == * Scalability: distribute query workload from backend to multiple cheap front-end systems. * Flexibility: achieve QoS, where each cache hosts different parts of the backend data, e.g., the data of Platinum customers are cached while that of ordinary customers are not. * Availability: by continued service for applications that depend only on cached tables even if the backend server is unavailable. * Performance: by potentially responding fast because of locality of data and smoothing out load peaks by avoiding round-trips between middle-tier and data-tier 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Database caching」の詳細全文を読む スポンサード リンク
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