With analytical column store DBs the standard is to do massive batches writes of thousands to millions of records at a time, vs. inserting individual records. Inserting individual records is basically always crazy inefficient with column stores. So a single write is generally for thousands to millions of records.

Buddy, if you look just a couple posts up you'll see me comment on how ClickHouse's actual disk format works. You don't need to explain batching to me.

Nonetheless you can't insert a-whole-file-and-just-that-file in less than one write.

Where does it say that? The pricing page says on "Writes" in the info tooltip: "Each write operation (INSERT, DELETE, etc) consumes write units depending on the number of rows, columns, and partitions it writes to."

This doesn't imply to me that each individual INSERT costs 1 WU, but that it could be fractional. I guess it depends on how you read it?

The tooltip has been changed since my comment was posted; it's now not incorrect, but it still doesn't really tell me more useful information.

(See https://news.ycombinator.com/item?id=33081099 for the original wording.)