6. Database Tailoring and Retrofitting Techniques › 6.3 Retrofitting Guidelines › 6.3.3 Retrofitting Archive Files › 6.3.3.1 Data Element Changes

6.3.3.1 Data Element Changes

Data element changes apply urgently to the online database,
but less urgently to the offline database.  That is, archive
files must be treated before the next archive update, and do
not necessarily have to be made simultaneously with the
online database retrofit and the permanent logic change.

In fact, the archive files really do not have to be
retrofitted until they are used.  The audit archive generally
contains one week's picture of the online files, which will
hold data of either the old values or the new values, but not
both.  The weekly and monthly history files are not created
in sorted order, and typically have to be sorted and
resummarized during use, anyway.  Thus it is possible to save
the retrofit logic and apply the logic when the archive is
used, rather than retrofit the entire archive.

There are several significant compromises with this
non-solution to archive maintenance.  The archive files
contain data for long periods, and may span several database
data element changes.  This means cumulative change logic
would have to be generated and tested, increasing the
possibility of harm to the offline database.

Changing data element values on archive files should be done
concurrently with the changes to the online database.  The
general recovery job templates shown in the previous section
work for cases in which the input and output SAS files can be
on the same DDname.  The same possibilities for file action
exist, according to the data element changed:

    - Value change only
    - Value change, order change, and granularity change