Unlike normal reporting, A/B testing collects data from a different combination of dimensions every time. It is also a complicated kind of analysis of immense data. In our case, we have a real-time data volume of millions of OPS (Operations Per Second), with each operation involving around 20 data tags and over a dozen dimensions.
For effective A/B testing, as data engineers, we must ensure quick computation as well as high data integrity (which means no duplication and no data loss). I'm sure I'm not the only one to say this: it is hard!