Abstract: A parallel query processing system comprises a front end processor, a query processing complex attached to the front end processor, and a database on a data repository attached by a first path to the front end processor, and by one or more additional paths to one or more slave processors within the query processing complex. An external operations command processor within the front end processor quiesces database managers in the slave processors to permit maintenance operations by the front end processor, and restarts the slave processors in read-only mode after maintenance operation completion. A splitter/scheduler function in a master processor within the query processor complex receives complex read-only queries from the front end processor, splits them into query elements, schedules the query elements for execution on the slave processors and recombines the execution results to be sent back to the front end processor.

Abstract: A computer network has a first computer which is locally coupled to a second computer. The first computer controls operation of the second computer according to a plurality of high level commands obtained from a third computer at a central station. The third computer includes apparatus for receiving the high level commands either from a program running on the third computer or an operator interface on the third computer. A communication facility is provided between the third computer and the first computer to transmit the high level commands to the first computer. The first computer includes a plurality of relatively low level programs corresponding respectively to the plurality of high level operation commands. Each of the low level programs implements the corresponding high level command to control operation of the first computer. The first computer also includes means for selecting the corresponding low level program in response to receipt of the high level command.