Our Mainframe Column Expansion engagements begin by establishing an inventory of the prime database columns or fields that will change. We specify the data types and lengths for each, and defining boundaries for the application of these changes across the enterprise.
We also review phased approaches to change with customer stakeholders and determine a disposition strategy. A single-phased approach allows all changes to be made and tested as a single process. A multi-phased approach requires bridges to be constructed and de-constructed between the applications, or data replication to accommodate phased implementation of the data and application changes.
Upon confirming disposition strategy, we specify data types, lengths, and boundaries for change in our Field Redefinition Workbench. The data origin definitions with target field lengths and data types are then used to establish a comprehensive Change Specification.
Once the origin of data elements is mapped alongside the target field lengths and data types, the next step is to assess the context of the adjustments outlined in the change specification. We perform an automated impact analysis to identify all references to the prime fields within the source code and all related fields in programs across the environment. This process provides our customers with the ability to customise and track statements of interest, and the option to establish boundaries to limit the scope of changes, and to flag generic fields to be ignored.
Following the review, adjustment, and acceptance of the impact analysis, modifications are applied to the prime fields and to all related program variables. Next, the conversion engine changes all related field definitions according to the application flow, without regard to field names. MOVE, IF, and PERFORM statements are modified to accommodate data type changes.