| 摘要 |
<p>PURPOSE:To reduce the overhead of data retrieval and to facilitate the restoration operation of a fault by permitting a request source system to directly access data at the time of retrieval and permitting a data base control source system to unitarily access data at the time of update. CONSTITUTION:When CPU 1a is the control source of the common data base DB 3, the DB access part 21 of CPU b2 directly accesses common DB 3 as to a retrieval request from the user program 22 of CPU b2. When there is dissidence in the contents of an index part and a data part in DB, the reading of DB data is retried for the number of prescribed times at prescribed intervals. The DB access part 11 of CPU a1 executes DB-access as to a update request from the user program of CPU b2 from the DB access part 21 of CPU b2 via a DB distribution function part 23, and the DB distribution function part 13 of CPU a1. Thus, DB retrieval performance becomes equal to access to uncommon DB and the restoration operation can easily be executed when the DB fault is restored.</p> |
