[mgkimsal]

I heard it put more succinctly as "schema on read" and "schema on write". "Schemaless" is really "schema on read" - you're making some assumptions about the structure/values you're reading out, and you plan to take specific actions based on those. "Schema on write" is... create db/table/column defs up front, and force the data adhere to that schema, so that when you read it out, there's no question about whether it conforms to expectations or not.

Per the article you linked to, yes, there's always a schema. When/how you decide to verify the assumptions about the data is the question.