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. |
- 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.
- For large tables with over 100 million records, use a scheduled task to implement data aging instead of modifying or setting TTL. To do this, run alter table table_name on cluster default_cluster drop partition partition_name.
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