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A TWO-LEVEL n-gram INVERTED INDEX STRUCTURE AND METHODS FOR INDEX BUILDING AND QUARY PROCESSING AND INDEX DERIVING OF IT
A TWO-LEVEL n-gram INVERTED INDEX STRUCTURE AND METHODS FOR INDEX BUILDING AND QUARY PROCESSING AND INDEX DERIVING OF IT
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机译:一种两层n-gram倒置索引结构及其索引构建,查询处理和索引推导的方法
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摘要
Disclosed relates to a structure of two-level n-gram inverted index and methods of building the same, processing queries and deriving the index that reduce the size of n-gram inverted index and improves the query performance by eliminating the redundancy of the position information that exists in the n-gram inverted index. The inverted index of the present invention comprises a back-end inverted index using subsequences extracted from documents as a term and a front-end inverted index using n-grams extracted from the subsequences as a term. The back-end inverted index uses the subsequences of a specific length extracted from the documents to be overlapped with each other by n−1 (n: the length of n-gram) as a term and stores position information of the subsequences occurring in the documents in a posting list for the respective subsequences. The front-end inverted index uses the n-grams of a specific length extracted from the subsequences using a 1-sliding technique as a term and stores position information of the n-grams occurring in the subsequences in a posting list for the respective n-grams.
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