Subsidiary index system

Abstract

Abstract PURPOSE:To improve the efficiency of direct access from a subsidiary key value and to efficiently perform the sequential access based on a primary key value thereafter by setting circumstances for sequential access by a second pointer in case of direct access based on a subsidiary index file. CONSTITUTION:When direct access from the subsidiary key value is requested, a subsidiary index file 9 is searched by a subsidiary key value 10a to obtain an objective subsidiary index record 10, and objective data is obtained from a data file 1 in accordance with a data address 10b. Since the subsidiary index record 10 has a primary index address 10c besides, the physical address of a primary index file 3 and the entry point of a corresponding primary index record 4 are set to access control information by information of the address 10c for the purpose of preparing for the following sequential access. Thus, the efficiency of direct access is improved and the efficiency of sequential access is improved.

Inventors

• 👤 Masahiro Ouchi

Bibliographic Details