It is common in legacy systems, particularly those using IMS or VSAM datastores to place small repeating groups of items into a single "record". This is often done for a variety of reasons but primarily to reduce the number of I/O requests or simplify what would otherwise be a hierarchical data structure. This is called Denormalization, and is the process of joining several relations together to avoid the cost of accessing several files/datastores instead of one. While this technique can be effective from a performance point of view it complicates the process of data transformation when the target datastore is fully normalized because for every source record processed multiple target records will be created or updated.
Connect CDC SQData was designed to facilitate the process of converting complex data structures into simple usable fully normalized data structures using existing data store descriptions, typically defined by a COBOL copybook containing an “occurs” statement. A special function, NORM is used to process each such repeating group in the source data description.