No one does it.

Oh, some people do. I used this EXACT phrase when I came in to fix an analytics system at a healthcare company that was plagued with analytics problems. They had 5 senior engineers, fulltime, working on this system for years. It had persistent problems and could not be modified in any meaningful way. Upstream systems sent data through multiple SQS topics (duplicate and out of order data) fed into lambda, fed into a giant cache-db which tried to catch dupes and order data, fed into files, processed in batch. It was a horror show in complexity and costing (despite the near-free lambdas). A distributed set of large data streams we feeding into a singular database which was processed, multiple times and put back in the same database. What's billions of inserts into an amazon postgres db, per hour? The company cloud infrastructure gave 0 other tools to work with. I shored up the batch processing (which had all kinds of try catch everywhere, despite a fixed schema) and went on to another company. Medical company software is always a ball of fail.