What approach to take?
The choice between a table/row-level migration approach and a unit of migration approach depends on the specific needs and characteristics of your data migration project. Each approach has its own advantages and disadvantages, and the decision should be based on factors such as data volume, complexity, data quality, and project goals. Here's a more detailed explanation to help you decide.
Table/Row-Level Migration Approach - ETL
Most data migrations based leveraing the strength of ETL tools apply a "Table/Row-Level Migration Approach"
The a advantages are faster and in many ways simpler for large scale migrations. Migrating entire tables or chunks of rows at once can be more efficient for high-volume data and It's relatively straightforward and may be suitable for migrations where minimal data transformation is needed.
This approach is often choosed when you need to move a large volume of data quickly and in scenarios where data transformation requirements are minimal or straightforward.
Unit of Migration Approach
Like some others (Johny Morris) hopp have taken the approach to define and migration "units of migration" calld Business Objects in hopp.
This approach have some clear advantages as it allows granular control for precise data transformation, validation, and enrichment on a per-unit basis. Its is a very flexibe and ideal for complex migrations with intricate business logic or data cleansing requirements. Finally, it enables the migration of specific records based on criteria.
Th obvious uses cases are when you need to perform complex data transformations during migration and validation. In these cases you want to be able to selectively migrate specific data based on rules or conditions.
A Hybrid Approach
In some cases, a combination of both approaches can be the best solution. You might start with a table/row-level approach for bulk data transfer and then apply unit of migration transformations on specific subsets of the data that require special handling.
Ultimately, the choice depends on the unique requirements of your data migration project. Consider factors like data complexity, volume, transformation needs, and performance requirements when making your decision. It's also essential to thoroughly plan and test your migration strategy to ensure a successful outcome.
.... also wrote a piece on Units of Migration approach in an article on the Support Site https://support.hopp.tech/en/support/solutions/articles/36000471626-unpacking-the-units-of-migration-approach-in-data-migration