The dashboard has to deal with a complex data integration problem, with different sources with differences in completeness, accuracy, age, and granularity (at many levels), daily corrections in past data, changes in data structure and semantics over time, large data volume, 4pm traffic spikes. Moreover, an API that allows you to select different metrics for different areas. Being able to simply write a SQL query or update and have it be fast regardless of volume is quite a life-saver if you have a tiny (mostly 1 person) team and development speed/adaptability is essential.

Some example queries issued by the dashboard: https://github.com/publichealthengland/coronavirus-dashboard... https://github.com/publichealthengland/coronavirus-dashboard... https://github.com/publichealthengland/coronavirus-dashboard...