How to Tune ClickHouse for Performance immediately after Installation


There are several things that you can do to tune ClickHouse performance immediately after installation:

  1. Configure the memory settings: Make sure that the configuration parameter max_memory_usage is set to a value that is appropriate for your use case. This parameter controls the maximum amount of memory that ClickHouse can use.
  2. Tune the number of threads: You can configure the number of threads that ClickHouse uses for different types of operations. For example, you can increase the number of threads used for SELECT operations to improve read performance.
  3. Configure the buffer size: You can configure the buffer size for different types of operations. This will help to minimize the number of disk I/O operations.
  4. Configure the merge settings: ClickHouse uses a MergeTree for some types of operations. You can configure the settings for this merge tree to improve performance.
  5. Configure the compression settings: You can configure the compression settings for different types of data. This will help to reduce the amount of disk space required to store the data.
  6. Configure the replica settings: If you are running a distributed setup, you can configure the replica settings to improve performance.
  7. Monitor the performance: After making these changes, you should monitor the performance of ClickHouse to see if the changes have had the desired effect.

Tuning Linux Server for ClickHouse Performance

There are several steps that can be taken to tune Linux for ClickHouse performance:

  1. Increase the number of open file descriptors: Increase the value of “ulimit -n” to at least 100000.
  2. Increase the amount of shared memory: Increase the value of “kernel.shmmax” to at least 1G.
  3. Configure transparent huge pages: Disable transparent huge pages by adding “transparent_hugepage=never” to the kernel command line.
  4. Configure the scheduler: Change the scheduler from the default “cfq” to “noop” or “deadline”.
  5. Optimize the network: Increase the number of network queues, enable TCP auto-tuning, and disable offloading options.
  6. Monitor system load: Use tools like “top” or “htop” to monitor system load, memory usage, and disk I/O.
  7. Monitor ClickHouse performance: Use the built-in ClickHouse performance monitoring tools to identify and troubleshoot performance bottlenecks.


It’s important to note that the specific tuning that’s required will depend on the specific hardware and workload, and it’s recommended to test different configurations to see which one works best.

To read more about configuration parameters in ClickHouse, do consider reading the below articles

About Shiv Iyer 222 Articles
Open Source Database Systems Engineer with a deep understanding of Optimizer Internals, Performance Engineering, Scalability and Data SRE. Shiv currently is the Founder, Investor, Board Member and CEO of multiple Database Systems Infrastructure Operations companies in the Transaction Processing Computing and ColumnStores ecosystem. He is also a frequent speaker in open source software conferences globally.