Information for the Database Administrator

Effects of Changing an ADABAS File or NATURAL DDM on Descriptor Files

Changes to an ADABAS file or NATURAL DDM can affect associated SAS/ACCESS descriptor files. If changes to ADABAS data invalidate your descriptor files, you must repair them manually by following these steps:

When you change an ADABAS file or NATURAL DDM, you must re-create the access descriptor(s) with PROC ACCESS, using the same access descriptor name(s).
Then you must update each view descriptor with PROC ACCESS. Change the view descriptor as needed.
The SAS/ACCESS interface view engine does a rudimentary validation of a view descriptor upon opening it. For example, the engine checks data type and data field grouping information. If a problem is found, the engine writes a message to the log and stops.

Before changing ADABAS data, consider the guidelines listed below.

Changes That Have No Effect on Existing View Descriptors

The following changes to an ADABAS file or NATURAL DDM have no effect on existing view descriptors:

creating ADABAS descriptors.
inserting new data fields.
deleting data fields not referenced in any view descriptor. (Note that if an access descriptor includes the deleted data field, users could eventually create a view descriptor using that data field, which would be a problem.)

Changes That Might Have an Effect on Existing View Descriptors

The following changes to an ADABAS file or NATURAL DDM might have an effect on existing view descriptors:

changing a data field name. If the data field name was used in selection criteria stored in the view descriptor, when you try to use the view descriptor, you will receive a syntax error message indicating an unrecognized data field name.
deleting ADABAS descriptor data fields if the field is used in selection criteria.

Changes That Cause Existing View Descriptors to Fail

The following changes to an ADABAS file or NATURAL DDM cause existing view descriptors to fail when they are used:

changing a numeric type to a character type.
changing a character type to a numeric type.
deleting a data field that is referenced in a view descriptor.
modifying a periodic group field or a multiple-value field. A field defined as a periodic group, a field within a periodic group, or a multiple-value field must retain its properties.
changing lengths that affect a SAS format. Certain ADABAS numeric types are changed to character hexadecimal when their lengths are too large for SAS to handle. You cannot change lengths that result in changing SAS formats from character to numeric or numeric to character.
changing superdescriptors, superfields, subdescriptors, and subfields. You cannot change the definition of these field types, such as adding or subtracting parentage information, changing the order of parentage information, or changing the from-to specification.

Top of Page