| 摘要 |
PROBLEM TO BE SOLVED: To permit fast file retrieval in a directory which has many files. SOLUTION: A storage device 2 stores hash values obtained by substituting the file name codes (numeral) of plural files to be retrieved in a prescribed hash function 12, a hash table 21 containing the numbers of directory blocks corresponding to the hash values, and a directory block 22; and the number of the directory block stored with directory entries are obtained corresponding to the hash values from the hash table 21 when the hash value is obtained by substituting a file name in the hash function 12. A file retrieval part 11 calculates the hash value corresponding to a file to be retrieved by using the hash function 12, specifies the mentioned number corresponding to the hash value by using the hash table 211, and retrieves a directory entry by limiting the retrieval to the directory block having the number.
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