The ATLAS Experience With Databases for Structured Data With Temporal and Hierarchical Order

Developing systems for the ATLAS (A Toroidal LHC ApparatuS) detector at LHC poses a new set of challenges like the storage of enormous amounts of data with different structures. This data is not only traditional Conditions Data which is slowly evolving data but also data from the online systems which cannot be stored with the event data but must be accessible from each event, like run information. Following the requirements from such systems we have developed a system which provides the facility to store structural data in a time order and with the possibility to classify hierarchically. We will also present a case study of use in the online systems of the ATLAS experiment where this system was used to store online data. Furthermore, we will show the different interfaces developed for this system and its use in different areas of application