SAS/ACCESS Interface to IMS-DL/I Software

Changing the Database and the Effects on Descriptors

Changes to the IMS-DL/I database can affect descriptor files. You must modify or re-create the descriptors if changes to the IMS-DL/I database invalidate the access or view descriptors. Use the ACCESS procedure to edit the affected access descriptors and view descriptors, or to create new descriptors.

If a view descriptor differs from the access descriptor, you receive a message. Re-create or edit the view descriptor as required. If you do not change your descriptor files, IMS-DL/I may return incorrect data to you. If the changes to the database involve numeric data, the procedure that uses the view descriptor could terminate abnormally. See UPDATE for information on editing descriptors.

Changing an item name has no effect on existing view descriptors. However, before you make other changes to IMS-DL/I databases, consider the guidelines described in the next section.

Changes That Cause Existing View Descriptors to Fail

The following changes to the IMS-DL/I database cause existing view descriptors to fail:

inserting or deleting segments in the middle of the hierarchy if you are updating the database
inserting or deleting a level in multiple occurring fields
changing the attributes of a field
deleting fields that are referenced in a view descriptor
inserting a field in the middle of a segment
adding fields to the end of database segments because longer segments may not be reflected in the RECORD statement's SEGLNG= argument.

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