Data migration has 2 main approaches based on the usage of the product. Big Bang data migration approach is less costly and less complex but more risky. Here the entire data is migrated at one go by maintaining a downtime. If you decide to take this approach, make sure to test the approach multiple times before going for the production data migration. Trickle data migration approach is less prone to unexpected failures reducing risk, close to zero-downtime, but is more costly and more time consuming. In this approach, you run 2 parallel systems by syncing data in the new system for testing during the transition period. Extensive tests are needed to identify any loopholes. Only when both systems are synchronized and tested successfully, the new system is switched to live mode. The time taken for data migration depends on various factors such as the size of the data, complexity of the data, the approach chosen, and the network speed. It can take anywhere from a few hours to several weeks.