Abstract: A system for concurrent processing of queries and transactions against a shared database. The system includes multiple processors wherein a processor is available for processing queries and another processor is available for concurrently processing transactions. A query buffer is established for performing the query search while the data accessed by transactions is available in a database cache. Control logic in a database management system distinguishes between transactions and queries and initiates file-read control for reading the file containing the database. File-read control contains logic for logical sequential reading and logical non-sequential reading of the file. Control structures provide a means for control over the load that the query is allowed to place on the system.

Abstract: A data base management system operating on a first host processor in a multi-host data processing environment performs consistency checking to detect the occurrence of an error. Based on the severity of the error condition, the data base management system may optionally notify the user of the error condition, save to a file the contents of memory allocated to the data base management system, or abort the data base management system. For error conditions which require either saving the allocated memory or aborting the data base management system, a message is automatically sent to the data base management systems operating on the other host-processors in the multi-host data processing environment. Upon receipt of the message indicative of the error condition, each of the receiving data base management systems saves to a file the contents of memory allocated on the host processor on which each of the receiving data base management systems is operating.