ClickHouse vs Elasticsearch: 8 key differences and how to choose

What is ClickHouse?

ClickHouse is an open-source columnar database management system for online analytical processing (OLAP) tasks. It handles high-performance querying and is optimized for large-scale data operations. Its architecture allows for efficient data compression, reducing storage costs while enabling rapid data retrieval. ClickHouse is popular in industries that require real-time data insights.

The system supports SQL queries, making it accessible to those familiar with traditional relational databases. ClickHouse’s columnar storage format ensures that only relevant data is read during query execution, enhancing performance. This results in faster query processing times compared to row-based databases, particularly for analytical workloads. Its scalability and distributed nature allow it to handle vast datasets efficiently.

What is Elasticsearch?

Elasticsearch is a distributed, RESTful search and analytics engine built on Apache Lucene. It’s known for scalability, speed, and reliability, making it a top choice for full-text search and log analytics. Elasticsearch can index structured, unstructured, time-series, and geospatial data, allowing users to query and visualize results quickly. It is widely used in applications requiring fast search and retrieval functions.

The strength of Elasticsearch lies in its ability to perform complex searches and data analysis in near real-time. It supports a variety of data types and provides built-in functions for data aggregation and filtering. Users can construct queries using its query DSL (domain specific language). Additionally, Elasticsearch is highly extensible and integrates with various data sources and visualization tools.

ClickHouse vs Elasticsearch: The key differences

1. Architecture

ClickHouse features a columnar storage architecture for analytical workloads, making it efficient for large-scale data processing. It organizes data in columns, optimizing for read-heavy operations, and reducing disk I/O. This architecture is ideal for OLAP queries, providing quick data retrieval and minimizing time spent on accessing unnecessary data. The distributed nature of ClickHouse allows it to scale horizontally, handling extensive datasets across multiple nodes.

Elasticsearch is built on a distributed document store architecture, optimized for full-text search and analytics. Its ability to index a wide range of data types makes it versatile for various applications, but it is particularly known for its high-speed search operations. Elasticsearch partitions data across nodes, ensuring redundancy and fault tolerance. Its architecture also allows for horizontal scaling, supporting large volumes of data and facilitating quick search operations.

2. Data storage

ClickHouse employs a columnar storage format that compresses and retrieves data quickly. This format allows ClickHouse to read only the necessary columns for a query, which speeds up data access and improves query performance for analytical tasks. Data is stored in a compressed format, reducing storage costs and enhancing retrieval times.

Elasticsearch uses a distributed document-based approach for data storage, storing data in JSON-like documents. This allows for flexible schema and quick data retrieval, making Elasticsearch suitable for full-text search and real-time analytics applications. Data is indexed to facilitate rapid search operations, supporting complex queries and aggregations on large datasets.

3. Indexing

ClickHouse does not use traditional indexing methods; instead, it relies on its columnar storage system for efficient data access. The lack of indexes means reduced storage overhead and maintenance complexity. ClickHouse’s performance hinges on its ability to perform large-scale reads quickly, rather than relying on indexes to filter data. This approach is effective for batch processing and analytical queries where full table scans are common and acceptable.

Elasticsearch heavily relies on indexing to support its high-speed search capabilities. It indexes every document allowing rapid search by keywords, terms, or patterns. This index-based retrieval is central to Elasticsearch’s functionality, enabling complex search queries and fast access to specific data points. While indexing increases storage and maintenance overhead, it is crucial for applications requiring precise search capabilities and real-time analytics.

4. Scalability

ClickHouse is designed for scalability, capable of efficiently handling petabytes of data across distributed clusters. Its architecture supports horizontal scaling, allowing organizations to add nodes and distribute workloads without sacrificing performance. This scalability is beneficial for industries that deal with large-scale data analysis and require reliable performance as data volumes grow. The system’s ability to partition work across nodes facilitates continuous operations and efficient resource utilization.

Elasticsearch is equally renowned for its scalability, providing horizontal scaling by distributing data across multiple nodes. It ensures data redundancy and fault tolerance, which is crucial for maintaining system uptime. Elasticsearch’s architecture allows for dynamic scaling, accommodating increased data loads and search queries without a drop in performance. This scalability makes it suitable for enterprises that require robust search capabilities and real-time analytics.

5. Licensing

ClickHouse operates under the Apache 2.0 open-source license, which grants users the freedom to use, modify, and distribute the software without significant restrictions. This permissive licensing model encourages wide adoption and contributions from the community. However, some features or support options may require commercial solutions from third-party vendors, especially for enterprise-level use.

Elasticsearch, originally released under the Apache 2.0 license, shifted to the Server Side Public License (SSPL) in 2021. The SSPL imposes stricter conditions on users who offer Elasticsearch as a service, requiring that the entire service’s source code be open-sourced under the same license.

6. Security

ClickHouse offers basic security features including user authentication and access controls, which are essential for managing data access and operations. While it provides transport encryption and network security measures, its security functionalities may require enhancements for enterprises with stringent compliance and data protection needs. Some organizations opt for additional external solutions to augment ClickHouse’s security layer.

Elasticsearch provides a set of security features as part of its Elastic Stack, offering access control mechanisms, encryption, and audit logging. It supports detailed user roles and permissions to enforce strict data access policies. Elasticsearch integrates with security tools and adheres to security best practices, making it suitable for environments with demanding security requirements.

7. Community

ClickHouse benefits from an active open-source community that contributes to its development and provides support resources. This community-driven approach enhances the software’s capabilities through regular updates, plugins, and documentation. Users can access forums, mailing lists, and GitHub repositories to collaborate and resolve issues.

Elasticsearch has a large and vibrant community, supported by Elasticsearch B.V., offering extensive resources for users and developers. The community produces a wealth of plugins, client libraries, and tutorials. Elasticsearch’s widespread adoption has created an ecosystem of developers and enthusiasts who contribute to troubleshooting and enhancing the software.

8. Use cases

ClickHouse is well-suited for use cases requiring efficient analytical data processing, such as time-series data analysis, real-time analytics, and event data management. Industries like finance and telecommunications, which process enormous data volumes, benefit from ClickHouse’s performance capabilities. Its rapid query performance and cost-effective storage solutions enable organizations to gain insights from complex and large datasets.

Elasticsearch best handles scenarios requiring full-text searches, log analysis, and real-time data monitoring, such as operational monitoring and application performance management. Its ability to handle diverse data types and perform fast queries makes it ideal for eCommerce search engines and social media analytics. Elasticsearch helps organizations gain quick insights into customer behavior and system performance.

ClickHouse vs Elasticsearch: How to choose?

These two systems excel in different areas—ClickHouse in high-performance analytical queries and Elasticsearch in full-text search and real-time analytics. However, the choice between them depends largely on the specific requirements of your use case:

• Data characteristics: Determine whether your primary focus is on structured analytical data or diverse document-based data. ClickHouse is ideal for structured, time-series data, whereas Elasticsearch thrives with unstructured, searchable content.
• Query complexity: For workloads demanding sophisticated analytics over vast datasets, ClickHouse is engineered for efficiency. Conversely, if your use case involves extensive keyword searches or pattern matching, Elasticsearch is better suited.
• Scaling strategy: Assess the nature of your growth. ClickHouse is better for scaling large-scale analytics operations, while Elasticsearch is more efficient for expanding search capabilities across distributed data environments.
• Response time and efficiency: Consider the importance of rapid query responses. ClickHouse offers high-speed performance for large-scale data analysis, whereas Elasticsearch is optimized for swift search results across large document stores.
• Total cost consideration: Analyze the overall cost, including infrastructure, maintenance, and scaling expenses. ClickHouse can be more cost-effective for large data analytics, while Elasticsearch might incur higher costs due to its extensive indexing and search capabilities.

Efficiency and scalability amplified: The benefits of Instaclustr for ClickHouse

Instaclustr provides a range of benefits for ClickHouse, making it an excellent choice for organizations seeking efficient and scalable management of these deployments. With its managed services approach, Instaclustr simplifies the deployment, configuration, and maintenance of ClickHouse, enabling businesses to focus on their core applications and data-driven insights.

Some of these benefits are:

• Infrastructure provisioning, configuration, and security, ensuring that organizations can leverage the power of this columnar database management system without the complexities of managing it internally. By offloading these operational tasks to Instaclustr, organizations can save valuable time and resources, allowing them to focus on utilizing ClickHouse to its full potential.
• Seamless scalability to meet growing demands. With automated scaling capabilities, ClickHouse databases can expand or contract based on workload requirements, ensuring optimal resource utilization and cost efficiency. Instaclustr’s platform actively monitors the health of the ClickHouse cluster and automatically handles scaling processes, allowing organizations to accommodate spikes in traffic and scale their applications effectively.
• High availability and fault tolerance for ClickHouse databases. By employing replication and data distribution techniques, Instaclustr ensures that data is stored redundantly across multiple nodes in the cluster, providing resilience against hardware failures and enabling continuous availability of data. Instaclustr’s platform actively monitors the health of the ClickHouse cluster and automatically handles failover and recovery processes, minimizing downtime and maximizing data availability for ClickHouse deployments.

Furthermore, Instaclustr’s expertise and support are invaluable for ClickHouse databases. Our team of experts has deep knowledge and experience in managing and optimizing ClickHouse deployments. We stay up-to-date with the latest advancements in ClickHouse technologies, ensuring that the platform is compatible with the latest versions and providing customers with access to the latest features and improvements. Instaclustr’s 24/7 support ensures that organizations have the assistance they need to address any ClickHouse-related challenges promptly.

For more information:

• Instaclustr for ClickHouse Now in Private Preview