What is ClickHouse


What is ClickHouse

ClickHouse is an open-source analytical database developed by Yandex to process large volumes of data at high speed. As a columnar database management system, it stores data by column, improving query speed by reading only relevant data. It supports real-time and historical workflows, enabling fast SQL queries across environments. Designed for scalability, it runs on a single server or multiple nodes with low latency. ClickHouse combines efficient storage, data compression, and a powerful engine to handle analytics on massive datasets, making it ideal for analysis, reporting, and data-driven applications in the cloud or on-premises. This is why it’s widely adopted by modern company data teams.

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What makes ClickHouse different?

ClickHouse stands out from other database systems because it’s purpose-built for analytics and ultra-fast processing. Rather than trying to handle every type of workload, it focuses on delivering fast execution and efficient storage for large-scale analysis. It’s widely used across modern software stacks, where teams learn, test, and refine their code through practical insights and continuous updates.

Here’s what sets it apart:

  • Columnar storage for faster queries
    ClickHouse stores data by column instead of by row. This means each query reads only the relevant data for improved efficiency and reduced unnecessary access.
     
  • Optimised for instant analytics
    It can process live data alongside historical data, so users can run commands and retrieve insights almost instantly. This makes it ideal for dashboards, monitoring, and reports.
     
  • Faster processing at scale
    ClickHouse is designed to handle large data volumes across different setups. Whether running on a single server or multiple nodes, it maintains peak efficiency even under heavy load.
     
  • Efficient compression and storage
    Built-in compression reduces storage requirements while improving read speed. This way, organisations can manage large datasets without excessive infrastructure costs.
     
  • Strong SQL support
    It’s compatible with standard queries, allowing developers and analysts to work with it easily without learning a new language.
     
  • Designed for analytical, not transactional tasks
    Unlike traditional DB systems, ClickHouse is not optimised for frequent updates or transactional operations. Instead, it excels at analysis and large-scale processing.
     
  • Flexible deployment options
    It can be deployed on-premises, in the cloud, or as part of a managed service, which means organisations can seamlessly integrate it into existing platforms and data management strategies.
     
  • Active community and ecosystem
    ClickHouse is backed by a strong community, frequent updates, and extensive documentation, helping users adopt and scale the database more easily.

Key features of ClickHouse

ClickHouse offers a range of powerful features designed to optimise workflows, latency, and storage efficiency. These capabilities make it particularly well suited for analytical tasks and large-scale environments.

  • Columnar storage architecture
    ClickHouse uses columnar storage to organise data efficiently, so analysis scans only what’s needed.  This reduces reads and boosts performance for analysis.
     
  • High-performance engine
    It’s a powerful engine that executes complex queries quickly, even on large datasets, delivering low latency for analytics and reporting. This is especially valuable for rapid insights and reporting.
     
  • Efficient data compression
    Built-in compression reduces storage usage and speeds up commands by limiting the amount of data read from disk, improving efficiency across large datasets and complex analytic workloads.
     
  • Scalable architecture
    It provides distributed deployment across multiple nodes, allowing it to scale horizontally as volumes grow. This makes it suitable for both single-server setups and large, cloud-based environments.
     
  • Instant and batch processing
    ClickHouse can handle live ingestion alongside historical data workflows, letting users run queries on fresher and existing data simultaneously.
     
  • Strong SQL compatibility
    ClickHouse supports queries, making it accessible for developers and analysts already familiar with relational DB systems.
     
  • Flexible deployment and cloud integration
    ClickHouse can be deployed on-premises, in the cloud, or as a managed service, offering flexibility in how organisations manage their setups.
     
  • Support for large-scale analytics
    It is specifically designed for analytical searches on large datasets, as well as analysis, observability, and business intelligence.
     
  • Active ecosystem and community support
    With extensive documentation, frequent updates, and strong community involvement, ClickHouse continues to evolve, with many developers actively contributing to its open source project and improving each version.

How does ClickHouse work?

ClickHouse processes large volumes of data quickly using columnar storage, a highly optimised engine, and distributed architecture. It is built for fast query execution, and scalable performance across different environments, including highly technical production systems.

Columnar storage and data organisation

  • Column-based storage: ClickHouse stores data in columns rather than rows. Queries read only what’s needed, cutting I/O and boosting performance for analytics.
  • Efficient compression: Data is compressed at the column level. Less data to read means lower storage usage and faster execution, especially at scale.
  • Optimised format: The storage format is tuned for fast access. Queries can scan billions of records efficiently without unnecessary overhead.

Distributed architecture and scalability

  • Distributed processing: ClickHouse can run across multiple nodes, enabling it to handle large-scale workflows and requests efficiently.
  • Scalable infrastructure: It can scale from one server to a clustered setup, depending on workload requirements.
  • Replication and fault tolerance: Data replication ensures availability and reliability, even in the event of node failures.

Query processing and execution engine

  • Highly responsive query engine: ClickHouse uses a powerful engine to execute queries quickly, even for complex analysis.
  • Parallel query execution: Queries are processed in parallel across multiple CPU cores and nodes, for lower latency.
  • Optimised execution paths: The system minimises unnecessary access, so each query retrieves only relevant data for faster results.

Data ingestion and management

  • Fast ingestion: ClickHouse handles high-speed insertion. Real-time and batch data are processed continuously without slowing requests, even when large volumes are retrieved and written simultaneously.
  • Real-time and historical queries: Queries run across recent and older data in a single pass. Analytics and reporting stay fast and consistent.
  • Flexible management: ClickHouse integrates with various sources and systems. Workflows and data pipelines stay efficient and easy to manage.

What is OLAP in ClickHouse

Online Analytical Processing (OLAP)  in ClickHouse refers to its ability to run fast analytics on large volumes of data. As an OLAP database, ClickHouse is optimised for analysis rather than transactional workloads. Its responsiveness makes it ideal for dashboards, reporting, and analysing real-time and historical data at scale.

What is ClickHouse Cloud

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ClickHouse Cloud is a serverless hosted DBMS solution that runs ClickHouse without requiring users to manage infrastructure. It handles deployment, scaling, and maintenance, allowing users to focus on data and commands. Designed for low-latency analysis, it delivers rapid processing on large volumes. With built-in replication, backups, and support for queries, it provides a reliable and scalable cloud environment for analytics operations, aligned with privacy policy, data security, and modern compliance requirements.

Benefits and drawbacks of ClickHouse

ClickHouse offers strong performance and flexibility for reporting, but it’s not suited to every use case. Here’s a balanced view:

Benefits

  • Low-latency query: ClickHouse is designed for fast reporting, and delivers instant insights even on large datasets, often outperforming competitors in benchmark and comparison tests.
  • Efficient storage: Columnar storage and compression reduce storage costs while improving read responsiveness.
  • Scalable architecture: It can run on one server or scale across various environments in the cloud.
  • Handles current and historical data: Users can query fresh and older data together for more complete analysis.
  • SQL support and flexibility: Familiar queries make it accessible for developers and analysts.

Drawbacks

  • Not suited for transactional workloads: ClickHouse is not designed for frequent updates or deletes, making it less ideal for Online Transaction Processing (OLTP) use cases.
  • Complex setup (self-managed): Managing infrastructure, scaling, and replication can be challenging without a managed service.
  • Limited row-level operations: Operations like updates and deletes are less efficient compared to traditional DB systems.
  • Learning curve for optimisation: Achieving optimal responsiveness may require understanding its architecture and data model.

Overall, ClickHouse is a powerful analytical database for high-speed processing, but it works best when used for the right type of workload.

ClickHouse applications (use cases)

ClickHouse is widely used for workloads that require fast queries on large amounts of data. Its efficiency and adaptability make it suitable for a variety of real-world applications.

Real-time analytics and dashboards

ClickHouse is often used to power high-speed dashboards by handling streaming data and enabling fast query execution. Businesses can monitor metrics, user activity, and performance indicators as events happen, enabling better decision-making.

Log and event reporting

It is particularly effective for analysing logs and events generated by applications, infrastructure, or systems. With the ability to process large volumes quickly, ClickHouse helps teams improve observability, detect issues, and optimise operations.

Business intelligence and reporting

ClickHouse supports analysis for business intelligence tools, allowing organisations to generate reports and explore data efficiently. Its ability to handle complex queries and large tables makes it ideal for data warehousing scenarios.

Product and marketing analytics

Teams use ClickHouse to analyse user behaviour, campaign performance, and product usage. By querying both fresh and historical data, organisations can gain deeper insights and improve their marketing and product strategies.

Data warehousing and large-scale workflows

ClickHouse can act as a powerful DB for managing and querying large amounts of structured data. Its distributed architecture and efficient storage make it suitable for handling growing workloads across cloud environments.

Discover Managed ClickHouse

OVHcloud offers a managed ClickHouse service that helps you run fast analytics on large volumes without managing the underlying infrastructure, so you can focus on insights instead of operations.

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Managed ClickHouse

Run a fully managed ClickHouse without handling infrastructure. OVHcloud takes care of deployment, scaling, maintenance, and updates, allowing users to focus on processing, SQL queries, and analytics. Designed for low-latency and reliability, it supports current and historical tasks with ease.

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Managed ClickHouse – Production

Designed for reliability and performance, this service helps you scale seamlessly, maintain availability, and deliver real-time insights across large datasets. Built-in replication, failover, and multi-zone deployment ensure reliable storage and consistent performance for critical analytical tasks.

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Managed ClickHouse – Discovery

Explore ClickHouse in a simple, low-commitment environment. Designed for testing, development, and smaller workloads, it offers a flexible way to run queries, explore features, and understand data handling before scaling to production. It’s ideal for getting started on the platform and assessing how it fits your data and analytics needs.