| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a data storage device, a data storage method and program that can, when accumulating data in a secondary memory device, maintain a speed close to that for a consecutive write-in file even if the sequence of data is reversed to some extent with respect to a key value, search for perfect matching according to the key value, efficiently read data in by range searching and, even if an abrupt substantial delay causes the data sequence to be reversed to a significant extent, realize a data structure capable of expressing the reversal at a high spatial efficiency. <P>SOLUTION: Sparse indexing is accomplished with respect to a specific value in a record as the key value, and, if a record of the key value included in a range of key values assigned to one logical block is in another logical block, offset data compressed by expressing the number of offsets from the one logical block to the other logical block in a bit string is recorded in a secondary memory device 330 as an offset file. <P>COPYRIGHT: (C)2013,JPO&INPIT |
