(Mux co-founder here) The Postgres system described as the predecessor to Clickhouse here actually was cstore_fdw with a pretty heavily customized (and outdated ) CitusDB. CitusDB is a great system for sharding and distributing postgres, but we found that the compression and query performance for this specific analytics use case was much better served by Clickhouse.

Cloudflare also moved from Citus to Clickhouse

The only place Citus is mentioned in the post is in the title of a chart. Might be worth updating to include this, would also clarify note #3:

"ClickHouse is still faster than the sharded Postgres setup at retrieving a single row, despite being column-oriented and using sparse indices. I'll describe how we optimized this query in a moment."

Not A-F1V3, but also a Mux co-founder.

To be transparent, we included Citus in original versions of the post, but decided to take it out because it didn't feel like it was a fair representation of Citus™. As Adam mentioned, what we were using was heavily customized and based on a pretty outdated fork by the time we transitioned.

This should be clarified in the post, otherwise you lead the reader to believe you're representing stock Postgres performance instead of the performance of a forked Citus. This is important information for an informed reader.