Abstract: In a database management method and a database management system in which transactions need not be stopped at a synchronization point (syncpoint) acquired at a fixed interval of time, when a point to acquire a syncpoint is reached in a database control procedure, a syncpoint acquisition start log is output and then a syncpoint acquisition flag is set ON in a page control table of each updated page existing in a buffer pool. In the operation, a list of update page control tables is also created to write in the database the pages which are indicated in the list thus prepared. However, for a transaction accessing the pertinent updated page prior to the write operation thereof in the database, the data write operation is performed before the page is referenced, thereby enabling the access to be performed to the database without interrupting the transaction.

Abstract: A database system is provided for reading data from a database to a database buffer and performing a physical sequential scan for the data on the buffer. If the preceding request for physical sequential scan is under execution, the database system operates to keep the succeeding request for scan in a waiting state until the preceding requested scan is completed and then execute the succeeding request for scan after the preceding requested scan is completed. If there are more than one succeeding requests for physical sequential scan, they are executed at the same time. Another scanning method is also provided. If the preceding request for scan is under execution, the succeeding requested scan is executed for the data existing after the halfway location at which the preceding scan process now reads the data. The short data is read from its head for completing the subsequent scan.

Abstract: In a composite subsystem having a plurality of data base systems and data communication on a plurality of processors, a composite subsystem controller unifies other data base systems of the composite subsystem and distributed data base systems, and, at the occurrence of a fault in some subsystem, allows other subsystems to operate continuously, thereby facilitating the recovery after the faulty subsystem has started up, and makes management as to which data base system a transaction in execution has accessed so that the range of failure is confined, thereby facilitating the fault recovery. The check points of two processings including updating of information in the memory and accumulation of the updated information in the journal are detected so that the need of journals earlier than the check point is eliminated, and a check point dump is acquired without waiting for the end of transaction which has been active at the check point.

Abstract: Task execution control for a multiprocessor wherein at a time point when a post issue task ends the use of a shared resource, the shared resource is released, another task which is running on another processor is allowed to lock the shared resource, and thereafter the task is made ready. After that, the post procedure is initiated, and thereafter through the high-speed dispatch procedure, the processor is granted first to a task which has failed to lock the shared resource, and the task is prompted to retry to lock the shared resource.

Abstract: In a composite system in which a plurality of data base systems and data communication are treated as respective subsystems. At the occurrence of a fault in one subsystem, other subsystems are allowed to operate continuously, thereby facilitating recovery after a faulty subsystem has started up. A controller performs as to which data base system a transaction in execution has accessed so that the range of failure is confined, thereby facilitating the fault recovery. The check points of two processings including updating of information in the memory and accumulation of the updated information in the journal are detected so that the need of journals for information occurring earlier than the check point is eliminated, and a check point dump is acquired without waiting for the end of a transaction which has been active at the check point.

Abstract: A distributed interactive processing in a complex computer system including a plurality of work stations (IWS's), each having predetermined server processes, at least a host computer (HOST), communication lines interconnecting between the plurality of IWS's and the HOSTs, and communication control portions to establish and to control communication paths between processes to conduct a process-to-process communication between the IWS's and the HOSTs. Each IWS has therein a process to implement an assigned processing request and a request control section to analyze the processing request issued by the own IWS and to determine a server process required to implement the processing request. Among a result of the request analysis, a predetermined server process is executed in the own IWS.