Accelerating 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. |
Note
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.