More helpful would be answers to my questions at https://news.ycombinator.com/item?id=33081502 - async_insert is a relatively new feature, we're still using buffer tables for example - but also most of our "client" inserts are actually onto multi-MV-attached null engines. Those MVs are also often doing some pre-aggregation before hitting our MTs as well. So we might insert a million rows, but the MV aggregates that down into 50k, but then that gets inserted into five persistent tables, each of which has its own sharding/partitioning so that blows up to 200k or something "rows" again. (And at some point those inserts are also going to get compacted into stuff inserted previously / concurrently by the MT itself.)

As I've said several times in this thread, I understand why you don't count inserts or rows. What I don't understand is what unit a WU does actually correspond to. In particular I don't understand its relation to e.g. parts or blocks, which are the units one would focus on optimizing self-hosted offerings.