Database migration for a webshop

One of our clients, a well-known fashion retailer, faced a major challenge. With a tight deadline, and a maximum of 6 hours downtime, the Oracle databases of the webshop system needed to be migrated to Microsoft SQL Server. As such, a TNG team was tasked with adapting the applications to the target database system and coordinating the data transfer in cooperation with internal and external colleagues.

A direct migration "in one go" was not possible due to the volume of data and the available network capacity. Instead, the team followed a two-step approach. Before the actual migration and while the system was running, the new database was pre-filled from a snapshot. During the downtime, the largest and most stable data tables were only updated, while smaller tables and fast-changing content structures were completely refilled.

The project was a success: after post-migration testing, the shop resumed full operation by the end of the planned downtime. Thanks to prior load tests and performance optimisations, the change went unnoticed by the end users. This new setup helps our client to manage growth in the coming years and paves the way for a future migration to the cloud.