What really matters for performance: lessons from a year of benchmarks

Tom Schreiber
9 min readbeginner
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Overview

The article discusses key benchmarks conducted over the past year that reveal insights into performance optimization in ClickHouse. It emphasizes the importance of efficient data movement and processing, showcasing several benchmarks that challenge existing assumptions about data storage and analytics.

What You'll Learn

1

How to leverage benchmarks to improve data ingestion performance in ClickHouse

2

Why using native formats and batching significantly enhances ingestion speed

3

When to implement distributed caching to reduce latency in analytics systems

4

How to perform fast updates in ClickHouse using standard SQL

5

Why understanding cost-performance metrics is crucial for cloud data warehouses

Key Questions Answered

How does ClickHouse handle JSON data compared to traditional data stores?
ClickHouse reimagines JSON storage on a columnar basis, resulting in unmatched speed and compression. Benchmarks show ClickHouse was thousands of times faster than traditional JSON stores like MongoDB, while also using significantly less storage.
What are the performance impacts of different input formats in ClickHouse?
The FastFormats benchmark revealed that native formats consistently outperform others in ingestion scenarios. Compression techniques like LZ4 and batch sizes significantly influence performance, with pre-sorting being less impactful than expected.
What architectural changes improve performance in cloud-native analytics?
The introduction of a distributed cache for ClickHouse Cloud significantly reduces latency for analytics queries. This shared caching layer allows for faster warm-ups and eliminates repeated downloads from object storage, outperforming traditional local SSD setups.
How fast are updates in ClickHouse compared to previous methods?
Standard SQL UPDATEs in ClickHouse are now up to 1,000× faster than classic mutations, with bulk updates finishing in milliseconds and single-row updates landing in tens of milliseconds, comparable to inserts.

Key Statistics & Figures

Speed improvement of ClickHouse over MongoDB
thousands of times faster
This was observed during the billion-docs JSON benchmark.
Cold queries ran up to
4× faster
This was achieved with the distributed cache compared to a local SSD setup.
Standard SQL UPDATEs speed improvement
up to 1,000× faster
This was compared to classic mutations in ClickHouse.
Rows aggregated in ~0.4 seconds
100 billion rows
This was achieved in the distributed GROUP BY benchmark.
Throughput achieved
240 billion rows per second
This was noted during the distributed GROUP BY benchmark.

Technologies & Tools

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Key Actionable Insights

1
Utilize benchmarks to challenge existing assumptions about data performance in ClickHouse.
By regularly measuring and analyzing performance, engineers can uncover surprising insights that lead to better system designs and optimizations.
2
Implement native formats and optimize batch sizes for data ingestion.
This approach can drastically improve ingestion speeds and reduce resource consumption, making it essential for high-throughput applications.
3
Adopt distributed caching strategies to enhance query performance in cloud environments.
This architectural shift allows for lower latency and better resource utilization, crucial for analytics workloads that demand quick response times.
4
Leverage ClickHouse's capabilities for fast updates to improve data management workflows.
With the new SQL UPDATE functionality, teams can maintain analytical performance while efficiently managing frequent data updates.
5
Focus on cost-performance metrics when evaluating cloud data warehouses.
Understanding how performance translates into cost can help organizations make informed decisions about their data infrastructure.

Common Pitfalls

1
Assuming that raw bandwidth is sufficient for performance without considering latency.
Many systems overlook the impact of latency on query performance, leading to suboptimal configurations. It's crucial to balance throughput with low-latency access to achieve desired performance levels.