A lot of times this is used for data warehousing so product managers and otherwise can query the database of one app joined with another, especially in an environment with microservices. You might join a table containing orders with another table that was from a totally different DB, like payments, to find out which kinds of items are best to offer BNPL or something.

The author also mentions that it’s used for machine learning models which will ultimately feed back into Shopify’s front end, for instance.