ClickHouse is an open source, high-performance, column-oriented database management system (DBMS) specifically designed for Online Analytical Processing (OLAP) and real-time data analytics. It has earned a reputation as a lightning-fast analytical database, with its performance maintained through the continuous addition of new features, performance enhancements, and crucial security patches.
While the desire to remain on a familiar, older version is understandable, not upgrading periodically will cause long-term issues. Skipping regular upgrades can cause your ClickHouse cluster to fall behind on essential database features, miss out on critical bug fixes or security fixes and ultimately become difficult to maintain.
In this blog, we’ll walk you step by step through everything you need to know about the importance of ClickHouse upgrades:
- Understanding ClickHouse releases: A breakdown of the different release types
- ClickHouse version numbering: A breakdown of versioning structure
- Benefits of upgrades: The importance of updating ClickHouse cluster regularly
Understanding ClickHouse release types
Before diving into the upgrade benefits, it’s important to understand how ClickHouse manages its releases. Unlike many traditional database systems that roll out major updates annually or less frequently, ClickHouse follows a continuous development model. To support this model, ClickHouse offers three distinct types of releases:
- LTS (Long-Term Support) releases:
- Purpose: Designed for production environments where stability is paramount
- Frequency: Typically released twice a year (March and August)
- Support window: Receives bug fixes and security patches for up to one year
- Best for: Production clusters requiring minimal disruption and long-term reliability
- Stable releases:
- Purpose: Regular monthly releases that include new features and improvements
- Frequency: Released every month
- Support window: Bug fixes for three months (three most recent stable releases)
- Best for: Non-critical environments, where frequent upgrades can be managed
- Pre-stable/testing releases:
- Purpose: Early access to experimental features and bug fixes
- Frequency: Released ahead of stable versions
- Support window: Limited support, not recommended for production workloads
- Best for: Testing and development environments to evaluate upcoming changes
Release type Stability Update frequency Support Recommended use LTS High Twice a year ~12 Months Production Stable Medium Monthly ~3 Months Non-critical Pre-stable/test Low Continuous Short-term Testing
ClickHouse version numbering
ClickHouse follows a structured version numbering system that helps users understand the nature and scope of each release. Here’s a breakdown of how it works:
Benefits of upgrading frequently
While an LTS (Long-Term Support) ClickHouse release provides a window of stability, the need to upgrade is inevitable. Instead of asking “why upgrade?”, a better question might be: What valuable improvements and safeguards are you missing by staying on an older version?
Upgrading regularly isn’t just about staying current—it’s about unlocking the full potential of ClickHouse while reducing risks in the long run. Examples of some of the key benefits you may get from an upgrade:
- Access to new features: ClickHouse evolves rapidly, and each release introduces powerful new capabilities. Regular upgrades ensure you can leverage:
- Enhanced SQL syntax and query capabilities
- New data types and functions (e.g., improved JSON handling, geospatial types)
- Improved observability through expanded system tables and metrics
- Enhancement for integrations (e.g., object storage improvements, new Kafka features)
- Performance improvements: Every ClickHouse release includes optimizations that can significantly improve:
- Query performance with new algorithms and better execution planner
- Resource efficiency by consuming less CPU, memory, or disk I/O for the similar workload
- Improved storage efficiency with enhanced MergeTree family engines, better compression, and faster data ingestion
- Security and stability: Older versions may lack critical patches and fixes. Regular upgrades ensure your cluster is protected against known vulnerabilities and provide:
- Critical security patches address newly identified vulnerabilities before they impact the system.
- Bug fixes and stability improvements: Staying with current version helps you with critical bug fixes, reduce the likelihood of unexpected crashes, or data inconsistencies.
- Easier maintenance: One of the most underestimated benefits is that latest versions are easy to maintain with available support:
- Community support is more accessible when you are on a recent, supported version.
- Improved documentation: Community discussions, examples, and documentation naturally revolve around current versions.
- Avoiding frustration: Debugging issues on outdated versions can be time-consuming and a frustrating experience.
- Reduce upgrade risk: Upgrading more frequently actually reduces the risk associated with the upgrade process itself. Here’s how:
- Fewer surprises: Staying close to the latest version means you’re less likely to encounter unexpected changes or deprecated features. The upgrade path is more predictable and better documented.
- Faster testing: With fewer changes between versions, testing becomes more efficient and feasible. You can validate compatibility with your queries, schema, and integrations without needing extensive regression testing.
- Lower chance of encountering broken or unsupported functionality: Skipping multiple versions increases the likelihood of hitting breaking changes or deprecated features. Frequent upgrades help you adapt incrementally.
- Avoiding technical debt: Postponing upgrades builds up a kind of technical debt. The gap between your current version and the latest release grows wider. Eventually, you’ll be forced to upgrade, and that single, massive leap will be far more complex, time-consuming, and risky. It may require rewriting queries, modifying schemas, or even re-engineering parts of your application code to ensure compatibility. By upgrading frequently, you address these challenges in small, manageable steps, keeping your system up to date and the upgrade process straightforward.
- Simpler rollback: If an issue arises, rolling back to the previous version is easier when the versions are close. Compatibility between adjacent releases is typically higher, reducing the risk of data format or schema mismatches.
- Ecosystem compatibility: Modern client libraries, connectors, and third-party tools are often tested against recent ClickHouse versions. Staying updated ensures:
- Smoother integration with cloud native services, other RDBMS platforms like PostgreSQL and MySql, BI tools, and streaming technologies like Kafka.
- Fewer compatibility issues when adopting new tooling or upgrading existing integrations.
Conclusion
Upgrading ClickHouse isn’t just about staying current with the latest version. It’s about ensuring your cluster remains secure, high-performing, and ready to meet future demands. Remember, the greatest risk in the ClickHouse upgrade lifecycle isn’t upgrading—it’s waiting too long. By making upgrades a regular part of your operational discipline, you avoid technical debt and unlock continuous performance improvements.
At NetApp Instaclustr, through our managed platform Instaclustr for ClickHouse, we maintain strict compatibility with ClickHouse standards and offer zero-downtime upgrades with every LTS release. Our customers benefit from a seamless upgrade experience, allowing them to focus on leveraging ClickHouse’s capabilities while we handle the operational complexity.
In the second blog of our upgrade series, we’ll explore the practical side of ClickHouse upgrades—discussing when and how often to upgrade and sharing best practices to help you carry out upgrades smoothly, safely, and with confidence.
