I have a question about routing. We are using ES for real-time analytics. We are routing documents based on a unique customer id field. We just noticed a big WARNING at the top of an article about routing that says we should no longer follow the advice in the article - https://www.elastic.co/blog/customizing-your-document-routing.
I'm trying to find some more details on which part of the article is now considered bad advice. Should we be using routing to ensure all data for a particular customer ends up on the same shard?