ClickHouse v21.11 Released

Rich Raposa
5 min readintermediate
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Overview

The ClickHouse v21.11 release introduces several significant features including asynchronous inserts, local interactive mode, executable user-defined functions (UDFs), predefined connections, and enhanced compression capabilities. These improvements aim to optimize data handling and user experience for ClickHouse users.

What You'll Learn

1

How to utilize asynchronous inserts for improved data ingestion performance

2

Why local interactive mode simplifies ad-hoc analytics on local files

3

How to implement executable UDFs for custom processing in ClickHouse

4

When to use predefined connections to streamline data source integrations

5

How to leverage compression for easier data import/export

Key Questions Answered

What are the benefits of using asynchronous inserts in ClickHouse?
Asynchronous inserts allow users to accumulate inserted data and store it in batches, reducing disk resource usage and enabling high rates of INSERT queries. This feature is particularly beneficial for scenarios with many clients sending data simultaneously, as it automates batch grouping and provides immediate acknowledgment of successful inserts.
How does local interactive mode enhance user experience?
Local interactive mode enables users to run ClickHouse commands directly without needing to connect to a server. This allows for quick analytics on local files and external data sources without the overhead of setting up a server, making it ideal for ad-hoc queries and testing hypotheses.
What are executable UDFs and how can they be used?
Executable UDFs in ClickHouse allow users to define functions in any programming language, enabling custom processing tasks like machine learning inference or DNS lookups directly within SQL queries. This flexibility enhances the functionality and usability of ClickHouse for various applications.
How do predefined connections simplify data source integration?
Predefined connections in ClickHouse allow users to connect to external data sources without repeatedly specifying credentials or addresses. By referencing these connections by name, users can streamline the process of loading data from sources like MySQL or S3, reducing configuration complexity.
What improvements does the compression feature bring to ClickHouse?
The new compression feature supports automatic detection and handling of compressed data during import and export operations. This simplifies the process of working with compressed files, allowing users to easily import/export data without manually specifying compression parameters.

Key Statistics & Figures

Number of committers
142
This reflects the collaborative effort behind the ClickHouse v21.11 release.
Total commits
4337
This indicates the level of development activity leading up to the release.
Release date
2021-11-09
This is the official release date for ClickHouse v21.11.

Technologies & Tools

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Key Actionable Insights

1
Utilize asynchronous inserts to enhance data ingestion performance, especially in high-throughput scenarios.
This feature is particularly useful for applications that require real-time data analytics, as it allows for smaller, concurrent inserts that are automatically batched, improving overall system efficiency.
2
Leverage local interactive mode for quick testing and analytics without server overhead.
This mode is beneficial for developers and data analysts who need to run exploratory queries on local datasets without the need for a full ClickHouse server setup.
3
Implement executable UDFs to extend ClickHouse's capabilities with custom functions.
This allows for more complex data processing tasks directly within SQL, making it easier to integrate external scripts and tools into your data workflows.
4
Use predefined connections to streamline the integration of external data sources.
This feature reduces the complexity of managing credentials and configurations, allowing for a more efficient workflow when connecting ClickHouse to various data sources.
5
Take advantage of the new compression feature for easier data handling.
This feature simplifies the import/export process for compressed files, making it easier to work with large datasets without additional steps.

Common Pitfalls

1
Failing to properly configure asynchronous inserts can lead to performance issues.
If users do not adjust the server-side settings for async inserts, they may not fully benefit from the performance improvements, resulting in suboptimal data ingestion rates.
2
Overlooking the need for predefined connections can complicate data source integration.
Without using predefined connections, users may find themselves repeatedly entering credentials and configurations, which can lead to errors and inefficiencies.