Tuning ClickHouse Configuration Parameters for High Performance


Tuning ClickHouse configuration parameters for performance can be a complex task, but there are a few key parameters that can have a significant impact on performance. Here is a general guide for tuning ClickHouse configuration parameters for performance.

Key ClickHouse Configuration Parameters

  1. Memory: Increasing the amount of memory allocated to ClickHouse can improve performance by allowing more data to be cached in memory. Parameters such as max_memory_usage, max_memory_usage_for_all_query and max_memory_usage_for_user can be used to control the amount of memory allocated to ClickHouse.
  2. Disk I/O: Monitoring disk I/O and ensuring that it is not a bottleneck is important for good performance. Parameters such as max_bytes_before_external_group_by, max_bytes_before_external_sort, max_parallel_replicas and readonly can be used to control disk I/O.
  3. Data Compression: ClickHouse uses data compression to reduce the amount of disk I/O required to read and write data. Parameters such as min_compress_block_size, min_part_size_for_compression, max_compress_block_size, max_part_size_for_compression can be used to control data compression.
  4. Data Partitioning: ClickHouse uses data partitioning to distribute data across multiple disks. Parameters such as num_shards, shard_weight, shard_count, replica_num, max_replicas, min_replicas can be used to control data partitioning.
  5. Concurrency: Parameters such as max_threads, max_concurrent_queries_for_user, max_concurrent_queries control the number of concurrent queries and threads that can be executed by ClickHouse.
  6. Indexing: Parameters such as min_index_granularity, max_index_granularity control the size of indexes, influencing the performance of queries.
  7. Network: Parameters such as listen_host, listen_port, http_port, tcp_keepalive_timeout control the network parameters of the ClickHouse server.
  8. Logging: Parameters such as log_level, log_queries, log_query_settings, log_query_threads control the logging options of the ClickHouse server.
  9. Monitoring: Parameters such as system_metrics_query_log_max_size, system_metrics_query_log_flush_interval_ms, system_metrics_query_log_flush_timeout_ms control the monitoring options of the ClickHouse server.


It’s important to note that each use case is different and what might work for one use case might not work for another. Therefore, it’s important to test different configurations, monitor the performance, and adjust the parameters as necessary.

Also, it’s a good idea to keep track of the changes you make and the results of the testing you do, so you can easily revert back to a previous configuration if necessary.

To know more about ClickHouse Configuration Parameters, please 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.