In the design stage of FATMEN, it was felt essential that the contents of the RZ files be backed up in a relational database. Some hundred thousand or more entries were eventually expected in the file catalogue and it was decided to back this data up in a reliable database with journaling, rollback and other recovery mechanisms. Normally, the full features of a relational database are not required, although they may well be exploited by the database manager to perform auditing and repair operations on the database. In addition, complicated queries can be performed much more easily using ORACLE than with the RZ database. These might be of use to generate a special extract of the database, such as all datasets older than a certain date.
A third reason has since arisen for the use of a separate database and this is again that of data integrity. The code path used to maintain the relational database is completely separate from that used to update the RZ files, greatly reducing the chance of data loss due to software. N.B. There is no requirement on any site to have ORACLE or any other relational database to run FATMEN. If selected, this code only ever runs in the server and is completely transparent to the user. The code involved will work with any relational database that provides a FORTRAN pre-compiler, including IBM's SQL/DS, DB2 etc.