Importance

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Abstract

An apparatus, method and program product for resubmitting queries encompassed by a Query Management Subsystem (QMS) responsive to high availability recovery actions within itself and a database subsystem it is designed to serve. The invention includes a work queue, a database subsystem, and a first QMS server which invokes and tracks queries in the work queue (received through traditional client interface means) as delivered to the database subsystem. A Query Resubmittal Mechanism (QRM) in the QMS is responsive to the database, client, and high availability recovery actions for both the QMS and database subsystem. The QRM modifies the status of queries in the work queue depending on whether a query has been submitted to the database or a database query response has been received. Incoming client queries are placed in the work queue (with queued status Q). Completed queries from the database are removed from the work queue and answer sets returned to the originating client. The QRM modifies the status of the oldest queries in the work queue from queued (Q) to active (A) and submits them to the database if the number of queries marked as active (A) in the work queue are under a user-defined, adjustable limit. The QRM determines if reconfiguration of the database subsystem has been completed in response to high availability recovery actions. QRM then modifies the adjustable limit and/or job priorities of the uncompleted queries if the database subsystem is operating in a degraded state (or returning to a repaired state) due to said reconfiguration. The work queue becomes durable by making it accessible to a backup, second server, and implementing a high availability configuration to restart the QMS/QRM on the backup server. When the QMS/QRM is started (after an operator shutdown) or restarted on the backup server (in the high-availability configuration), the QRM interrogates the work queue to determine if it contains uncompleted queries and resubmits them, up to the adjustable limit.

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First Claim