Facebook is rolling out Off-Facebook Activity tool to allow people to see apps and websites that choose to share activity with us and to disconnect that activity from their accounts. Facebook says it is working on a redesign of the way our systems store and process this activity. We are sharing the story of how we did this, with some of the lessons we learned along the way, with the hope that this may help others interested in building their own data transparency tools. In order to show people a summary of their activity, we built a centralized copy of key data points that can be queried in real time.”]
Source: https://engineering.fb.com/2019/08/20/data-infrastructure/off-facebook-activity/