Development of a Data Warehouse is one of the vital tasks expected to yield major business benefits with regards the justification of the cost and efforts. However, many ETL projects fail to achieve the required benefits due to improper quality assurance strategy. Data Migration Testing ensures the data migrated from varied sources to the data warehouse occurs with no loss of information/ data, adhering strictly to transfer rules, in abidance with validity checks. ETL testing should be continuous to sew up the extraction, transformation, and load processes working as planned and the result is consistent, accurate, and complete.
In a big bang data migration, the full transfer is completed within a certain time frame, requiring relatively little time to complete.
Trickle migrations, completes the migration process in phases. During implementation, the old system and the new are run in parallel, which eliminates downtime or operational interruptions.