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

The database services for the distributed application environment of the HE RA-13 experiment are presented. Achieving the required 10(6) trigger reduct ion implies that all reconstruction. including calibration and alignment pr ocedures, must run online, making extensive usage of the database systems. The associations from the events to the database objects are carefully intr oduced considering efficiency and flexibility. The challenges of managing t he slow control information were addressed by introducing data and update o bjects used in special processing on dedicated servers. The system integrat es 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 databas es, the relevant data is replicated using a relational database management system. (C) 2001 Elsevier Science B.V. All rights reserved.