Part 1: Introduction & Architecture
What is ClickHouse, why is it so fast, and how does it work under the hood?
Welcome to “ClickHouse: From Zero to Hero”. In this first part, we’ll explore what makes ClickHouse the fastest OLAP database on the planet.
What is ClickHouse?
ClickHouse is an open-source column-oriented database management system (DBMS) for online analytical processing (OLAP). It allows generating analytical reports using SQL queries in real-time.
Row-Oriented vs. Column-Oriented
Row-Oriented (MySQL, Postgres)
Data is stored row by row. Great for transactional workloads (OLTP) where you need to fetch or update a single user’s record.
Column-Oriented (ClickHouse)
Data is stored column by column. Great for analytical workloads (OLAP) where you want to calculate the average price of all orders.
Why is it so fast?
Columnar Storage: Only reads the columns you need.
Compression: Columnar data compresses extremely well (LZ4, ZSTD).
Vectorized Execution: Processes data in blocks, utilizing modern CPU SIMD instructions.
Parallel Processing: Utilizes all available CPU cores.
Conclusion
ClickHouse is designed from the ground up for speed. In the next part, we’ll get our hands dirty and install ClickHouse.