merge_* MergeTree table settings

ClickHouse MergeTree table settings in the merge_* generated group.

These settings are available in system.merge_tree_settings and are autogenerated from ClickHouse source.

merge_total_max_bytes_to_prewarm_cache

Only available in ClickHouse Cloud. Maximal size of parts in total to prewarm cache during merge.

merge_use_batch_sorting_queue

Use the batch sorting queue to reduce per-row queue overhead when merging sorted streams.

Only applies to merges that do not change rows, i.e. plain MergeTree (Ordinary merge mode). It has no effect on engines with merge-time semantics such as ReplacingMergeTree, CollapsingMergeTree, SummingMergeTree, AggregatingMergeTree, CoalescingMergeTree, GraphiteMergeTree and VersionedCollapsingMergeTree, which keep using the default queue regardless of this setting.

merge_workload

Used to regulate how resources are utilized and shared between merges and other workloads. Specified value is used as workload setting value for background merges of this table. If not specified (empty string), then server setting merge_workload is used instead.

See Also

• Workload Scheduling