Bit string search device, search method, and program

Abstract

A terminal node the value of a discrimination bit position of which is smaller than 0 is first stored in a search route stack for storing a search history and branch nodes followed by way of the search route are sequentially stored in order to prevent the efficiency of a search processing using a coupled node tree from being reduced even if the size of the coupled node tree is increased. On that occasion, the representative node number of the branch nodes, if the link destination is node [1], is changed into the value to which 1 is added. The hit ratio of a cache can be increased in the search processing to improve the efficiency of the processing by storing the branch nodes in the search route stack.

Description

technical field [0001] The present invention relates to a search device, a search method and a program for searching a desired bit sequence from a set of bit sequences, and particularly relates to the technical field of researching a data structure for storing a bit sequence to improve the search speed and the like. Background technique [0002] In recent years, the informatization of society has continued to develop, and large-scale databases have been used everywhere. In order to search for records from such a large-scale database, it is common to search for a desired record by using, as an index key, an item in a record corresponding to an address where each record is stored. Moreover, character strings in full-text search can also be regarded as index keywords of documents. [0003] Moreover, since these index keywords are expressed by bit sequences, the retrieval of the database can be attributed to the retrieval of bit sequences. [0004] In order to perform the bit ...

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Problems solved by technology

[0015] As described above, in the retrieval process using the Patricia tree, there are advantages such as that the retrieval can be performed only by checking the necessary bits, and that all keywords need only be compared once. However, there are disadvantages such as the following: The storage capacity increases due to two links from the node, the judgment process is complicated by the existence of the reverse link, and the search processing delay and addition and deletion are caused by comparison with the index key after the reverse link returns. Data maintenance is difficult

[0017] However, in the technique disclosed in Patent Document 1 below, since one node always occupies the index key area and the pointer area, the lower left and right nodes are stored in consecutive areas and one pointer is used. figure 1 The lower part of the Patricia tree shown, namely the left pointer 1740c, the right pointer 1741h, etc., must also allocate a storage area with the same capacity as the node, and the reduction effect of the storage capacity is not very good.

In addition, it does not improve the delay of retrieval processing caused by backlinks, and it is difficult to perform processing such as addition and deletion.

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