As I indicated earlier, I am a devotee of data modelling when it comes to data migration. What I present here are some (reasonably) simple examples of how to use data models to spot data gaps and how to use data models to help bridge them.

Data gap analysis should be a first-order task before the detailed Data Mapping occurs. As we shall see, it informs our selection and navigation rules. By taking the ‘helicopter view‘ that data modelling provides we can confront gaps in the legacy data early. And the earlier we confront them, the better. There are, however, limitations to data modelling:

  • It can only verify that the structure is correct, it cannot perform a Reality Check.

  • It cannot necessarily reveal that look-up data matches ...

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