We have designed a metadata database containing all information stored in almost 10 million FITS file headers using Sybase IQ server. This repository includes metadata from raw observation frames and from the science and calibration pipeline products produced by the ESO Quality Control group. We present a few illustrative applications using data stored in this database. One of the applications which is very attractive to the astronomical community is the possibility to access the FITS headers with up-to-date information coming directly from the database using the ESO Archive interface. The keyword repository can also feed local tables and/or views for specific uses, such as instrument specific tables, which contain parameters specific to particular instruments used in archive queries. Finally, the ESO observation keyword repository supports Virtual Observatory applications with the meta-data needed by visualisation tools, such as VirGO or Aladin.
We present the design of the system for handling observations metadata at the Science Archive Facility of the
European Southern Observatory using Sybase ASE, Replication Server and Sybase IQ. The system has been reengineered
to enhance the browsing capabilities of Archive contents using searches on any observation parameter,
for on-line updates on all parameters and for the on-the-fly introduction of those updates in files retrieved from the
Archive. The systems also reduces the replication of duplicate information and simplifies database maintenance.