The solution is to use an ETL (Extract, Transform, and Load) tool to copy data to a warehouse. You then point the BI tool at the warehouse. There are lots of

The solution is to use an ETL (Extract, Transform, and Load) tool to copy data to a warehouse. You then point the BI tool at the warehouse. There are lots of tools for this already, and even more custom solutions and other things. CSV files tend to rule here... scheduled exports that are picked up by the ETL tools. The transformations that take place are usually normalisation of data from systems of differing schema or different types of data (perhaps changing strings into corresponding numbers, i.e. Risk Level = Orange could be normalised as 50% in the data warehouse). Businesses have taken this approach for a long long time as the databases that drive applications, services, and now micro-services have always been tuned for the performance of the production use-case and not for ad-hoc reporting.