Company
Date Published
Author
Tom Schreiber
Word count
3465
Language
English
Hacker News points
None

Summary

The ClickHouse relational database management system is optimized for real-time analytics, allowing fast query execution with minimal tuning. To accelerate queries, utilize primary indexes to minimize disk reads, ensuring the table's rows are stored in a sorted order that can be efficiently searched by index. Properly utilizing primary indexes allows terabytes of data to be skipped and searched in a matter of seconds. Additionally, creating a second table with a different row order based on a different primary key can optimize queries for specific conditions, such as filtering by town. Furthermore, ClickHouse's Projections feature enables the creation of additional tables that automatically keep data in sync with the original table, allowing for incremental aggregation and multiple row orders. Increasing query processing parallelism also speeds up execution time by utilizing more threads to process data in parallel. By applying these techniques, users can optimize performance for specific queries and minimize disk reads, resulting in faster query execution times.