Hi, the wording could probably use some tidying up around that part and I'm open to suggestions. However, I do think it's a big problem with columnar based time series databases.

When somebody wants to query for a few points matching certain dimensions in Cassandra there's no getting around the fact that you have to do a scan across potentially billions of data points.

Whereas if the index lives outside in something relational like Postgres the lookup becomes insanely cheap and you're not having to scan over a bunch of data.

There are quite a few databases that don't have an efficient external index. For those, running 10 times the number of nodes would certainly speed things up, but it's probably just a good idea to avoid databases like that if you want fast queries.