Updated on 2024-10-09 GMT+08:00

Accelerating ClickHouse TTL Operations

When TTL is triggered in ClickHouse, a large amount of CPU and memory are consumed.

Log in to FusionInsight Manager and choose Cluster > Services > ClickHouse. Click Configurations then All Configurations. Click ClickHouseServer > Customization, find the clickhouse-config-customize parameter, add the following parameters, save the configuration, and restart the service.

Configuration Item

Reference Value

Description

merge_tree.max_replicated_merges_with_ttl_in_queue

Half of number of CPU cores

Number of tasks that allow TTL to merge parts concurrently in the ReplicatedMergeTree queue.

merge_tree.max_number_of_merges_with_ttl_in_pool

Number of CPU cores

The thread pool that allows TTL to merge parts in the ReplicatedMergeTree queue.

Do not modify these configurations when the cluster writes heavily. Idle threads need to be reserved for regular Merge operations to avoid the "Too many parts" issue.