| 摘要 |
PROBLEM TO BE SOLVED: To allow processing map data and the like at high speed. SOLUTION: A map server 10 has a map database 11 in which much of mesh data is registered. The database 11 is constituted as a layered file system in which each name of directory and file is composed of a minimum number of letters. A storing position when caching is pre-decided with dividing a mesh number based on the position coordinates by a size of a cache area 35 and acquiring the rest. When searching cache data, the position in the area 35 is acquired from the number of a desired file to directly detect data at the position. If unnecessary data is stored, the data is deleted to release the storage area.
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