Patent ID: 6678687
Filing Date: 2004-01-13
Classification: G06F,Y10S

Abstract:
A method for creating an index in which keys are associated to search for a value from a specified key, comprising:constituting the index to register sets of keys and values by providing a B+ tree index that is split to a plurality of subindexes; and storing each of the subindexes in a two-dimensional array position referenced in a first dimension by a value determined by applying a predetermined function to a value to be registered and referenced in a second dimension by a value determined by applying a predetermined function to a key; wherein a word is used as the key and one document containing the word is used as the value; wherein a document identification number and a word identification number are assigned to the document and the word, respectively, to uniquely identify them; wherein, as the function to apply to documents, a hash function is provided that maps the document identification number to the value indicating a position of one dimension of the two-dimensional array, and as the function to apply to words, a hash function is provided that maps a word identification number to a value indicating a position of another dimension of the two-dimensional array; and wherein an occurrence of a word in a document is registered in a corresponding subindex by using values obtained by applying the hash functions.