Let's optimize one aggregate function in ClickHouse [ru]
Let's calculate an average of one column for each key, like the following query: SELECT key, avg(value) FROM table GROUP BY key. What can be more simple? But the question is: what is the most efficient way to do it? How to write code to achieve maximum performance on a variety of hardware?
- Dev Lead at Yandex
- Since 2008 has been developing data storage systems for Yandex Metrica
- ClickHouse project founder and developer