[wiredfool]

My first big win for clickhouse was replacing a 1.2tb, billion + row postgresql DB with clickhouse. It was static data with occasional full replacement loads. We got the DB down to ~ 60GB, with query speeds about 45x faster.

Now, the postgres schema wasn't ideal, and we could have saved ~ 3x on it with corresponding speed increases for queries with a refactor similar to the clickhouse schema, but that wasn't really enough to move the needle to near real-time queries.

Ultimately, the entire clickhouse DB was smaller than the original postgres primary key index. The index was too big to fit in memory on an affordable machine, so it's pretty obvious where the performance is coming from.

[hodgesrm]

This is a nice illustration of the effects of different choices for storage layout and use of compute. ClickHouse blows away single-threaded queries on row-based data for analytic questions. On the other hand PostgreSQL can offer far higher throughput and concurrency when updating a shopping cart.