The HERA-B database services: for detector configuration, calibration, alignment, slow control and data classification Original Research Article

The database services for the distributed application environment of the HERA-B experiment are presented. Achieving the required 106 trigger reduction implies that all reconstruction, including calibration and alignment procedures, must run online, making extensive usage of the database systems. The associations from the events to the database objects are carefully introduced considering efficiency and flexibility. The challenges of managing the slow control information were addressed by introducing data and update objects used in special processing on dedicated servers. The system integrates the DAQ client/server protocols with customized active database servers and relies on a high-performance database support toolkit. For applications that required complex selection mechanisms, as in the data-quality databases, the relevant data is replicated using a relational database management system.