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In computer science, a grid file or bucket grid is a point access method which splits a space into a non-periodic grid where one or more cells of the grid refer to a small set of points. Grid files (a symmetric data structure) provide an efficient method of storing these indexes on disk to perform complex data lookups. It provides a grid of ''n''-dimensions where ''n'' represents how many keys can be used to reference a single point. Grid files do not contain any data themselves but instead contain references to the correct bucket. ==Uses== A grid file is usually used in cases where a single value can be referenced by multiple keys. A grid file began being used because "traditional file structures that provide multikey access to records, for example, inverted files, are extensions of file structures originally designed for single-key access. They manifest various deficiencies in particular for multikey access to highly dynamic files." 〔J. Nievergelt, H. Hinterberger ''The Grid File: An Adaptable, Symmetric Multikey File Structure''. Institut fur Informatik, ETH and K. C. Sevcik, 1984. Abstract, pp.1.〕 In a traditional single dimensional data structure (e.g. hash), a search on a single criterion is usually very simple but searching for a second criterion can be much more complex. Grid files represent a special kind of hashing, where the traditional hash is replaced by a grid directory. 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「grid file」の詳細全文を読む スポンサード リンク
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