Troubleshooting
- Log in to the ClickHouse client and check whether abnormal merge exists.
select database, table, elapsed, progress, merge_type from system.merges;
- Do not perform the INSERT operation too frequently, do not insert a small amount of data, and increase the interval for inserting data.
- The data table partitions are not properly allocated. As a result, too many partitions are generated and data tables need to be re-partitioned.
- If the MERGE operations are not triggered or slow, adjust the following parameters to accelerate them.
For details, see Accelerating Merge Operations.
Configuration Item
Reference Value
max_threads
Number of CPU cores x 2
background_pool_size
Number of CPU cores
merge_max_block_size
The value is an integer multiple of 8192 and is adjusted based on the CPU and memory resources.
cleanup_delay_period
Set this parameter to a value that is appropriately less than the default value 30.
Changing the Value of parts_to_throw_insert
Increase the value of this parameter only in special scenarios. This configuration acts as a warning for potential issues to some extent. If the cluster hardware resources are insufficient and this configuration is not adjusted properly, potential service issues cannot be detected in a timely manner, which may cause other faults and increase the difficulty of fault recovery.
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 configuration, save it, and restart the service.
Name |
Value |
|---|---|
merge_tree.parts_to_throw_insert |
Memory of ClickHouse instances/32 GB x 300 (conservative estimation) |
Verify the modification.
Log in to the ClickHouse client and run the select * from system.merge_tree_settings where name = 'parts_to_throw_insert'; command.