Google now allows you to develop apps using BigTable (hosted as a product called "Cloud Bigtable" in Google Cloud Platform). However, I can't find too many example on how to design a schema for it. They have a document, but it's very high level: https://cloud.google.com/bigtable/docs/schema-design
My Question: what's the approximate schema for gmail (just the email list component). Is it a tall or wide design? What do they use for primary keys?
Any other production examples from big apps would be appreciated, but I think Gmail would be a great example.