MergeTree tables settings

The time is relative to the time of the most recent record, not to the wall
time. If it's the only record it will be stored forever.

## replicated\_fetches\_http\_connection\_timeout[​](#replicated_fetches_http_connection_timeout "Direct link to replicated_fetches_http_connection_timeout")

Obsolete setting, does nothing.

## replicated\_fetches\_http\_receive\_timeout[​](#replicated_fetches_http_receive_timeout "Direct link to replicated_fetches_http_receive_timeout")

Obsolete setting, does nothing.

## replicated\_fetches\_http\_send\_timeout[​](#replicated_fetches_http_send_timeout "Direct link to replicated_fetches_http_send_timeout")

Obsolete setting, does nothing.

## replicated\_fetches\_min\_part\_level[​](#replicated_fetches_min_part_level "Direct link to replicated_fetches_min_part_level")

Minimum part level to fetch from other replicas. Parts with level below this threshold are postponed
(kept in the replication queue and re-evaluated each scheduling cycle, not permanently skipped).
Use 1 to postpone fetching level-0 (unmerged) parts, reducing replication overhead during heavy ingestion.
Default: 0 (fetch all parts regardless of level).

## replicated\_fetches\_min\_part\_level\_timeout\_seconds[​](#replicated_fetches_min_part_level_timeout_seconds "Direct link to replicated_fetches_min_part_level_timeout_seconds")

Timeout in seconds after which a part below replicated\_fetches\_min\_part\_level will be fetched anyway.
Use 0 to disable the timeout (parts below the minimum level are postponed indefinitely until merged).
Default: 300 (force fetch after 5 minutes).

## replicated\_max\_mutations\_in\_one\_entry[​](#replicated_max_mutations_in_one_entry "Direct link to replicated_max_mutations_in_one_entry")

Max number of mutation commands that can be merged together and executed in
one MUTATE\_PART entry (0 means unlimited)

## replicated\_max\_parallel\_fetches[​](#replicated_max_parallel_fetches "Direct link to replicated_max_parallel_fetches")

Obsolete setting, does nothing.

## replicated\_max\_parallel\_fetches\_for\_host[​](#replicated_max_parallel_fetches_for_host "Direct link to replicated_max_parallel_fetches_for_host")

Obsolete setting, does nothing.

## replicated\_max\_parallel\_fetches\_for\_table[​](#replicated_max_parallel_fetches_for_table "Direct link to replicated_max_parallel_fetches_for_table")

Obsolete setting, does nothing.

## replicated\_max\_parallel\_sends[​](#replicated_max_parallel_sends "Direct link to replicated_max_parallel_sends")

Obsolete setting, does nothing.

## replicated\_max\_parallel\_sends\_for\_table[​](#replicated_max_parallel_sends_for_table "Direct link to replicated_max_parallel_sends_for_table")

Obsolete setting, does nothing.

## replicated\_max\_ratio\_of\_wrong\_parts[​](#replicated_max_ratio_of_wrong_parts "Direct link to replicated_max_ratio_of_wrong_parts")

If the ratio of wrong parts to total number of parts is less than this -
allow to start.

Possible values:

- Float, 0.0 - 1.0

## search\_orphaned\_parts\_disks[​](#search_orphaned_parts_disks "Direct link to search_orphaned_parts_disks")

ClickHouse scans all disks for orphaned parts upon any ATTACH or CREATE table
in order to not allow to miss data parts at undefined (not included in policy) disks.
Orphaned parts originates from potentially unsafe storage reconfiguration, e.g. if a disk was excluded from storage policy.
This setting limits scope of disks to search by traits of the disks.

Possible values:

- any - scope is not limited.
- local - scope is limited by local disks .
- none - empty scope, do not search

## serialization\_info\_version[​](#serialization_info_version "Direct link to serialization_info_version")

Serialization info version used when writing `serialization.json`.
This setting is required for compatibility during cluster upgrades.

Possible values:

- `basic` - Basic format.
- `with_types` - Format with additional `types_serialization_versions` field, allowing per-type serialization versions.
  This makes settings like `string_serialization_version` effective.

During rolling upgrades, set this to `basic` so that new servers produce
data parts compatible with old servers. After the upgrade completes,
switch to `WITH_TYPES` to enable per-type serialization versions.

## shared\_merge\_tree\_activate\_coordinated\_merges\_tasks[​](#shared_merge_tree_activate_coordinated_merges_tasks "Direct link to shared_merge_tree_activate_coordinated_merges_tasks")

Activates rescheduling of coordinated merges tasks. It can be useful even when
shared\_merge\_tree\_enable\_coordinated\_merges=0 because this will populate merge coordinator
statistics and help with cold start.

## shared\_merge\_tree\_create\_per\_replica\_metadata\_nodes[​](#shared_merge_tree_create_per_replica_metadata_nodes "Direct link to shared_merge_tree_create_per_replica_metadata_nodes")

Enables creation of per-replica /metadata and /columns nodes in ZooKeeper.
Only available in ClickHouse Cloud

## shared\_merge\_tree\_disable\_merges\_and\_mutations\_assignment[​](#shared_merge_tree_disable_merges_and_mutations_assignment "Direct link to shared_merge_tree_disable_merges_and_mutations_assignment")

Stop merges assignment for shared merge tree. Only available in ClickHouse
Cloud

## shared\_merge\_tree\_empty\_partition\_lifetime[​](#shared_merge_tree_empty_partition_lifetime "Direct link to shared_merge_tree_empty_partition_lifetime")

How many seconds partition will be stored in keeper if it has no parts.

## shared\_merge\_tree\_enable\_automatic\_empty\_partitions\_cleanup[​](#shared_merge_tree_enable_automatic_empty_partitions_cleanup "Direct link to shared_merge_tree_enable_automatic_empty_partitions_cleanup")

Enabled cleanup of Keeper entries of empty partition.

## shared\_merge\_tree\_enable\_coordinated\_merges[​](#shared_merge_tree_enable_coordinated_merges "Direct link to shared_merge_tree_enable_coordinated_merges")

Enables coordinated merges strategy

## shared\_merge\_tree\_enable\_keeper\_parts\_extra\_data[​](#shared_merge_tree_enable_keeper_parts_extra_data "Direct link to shared_merge_tree_enable_keeper_parts_extra_data")

Enables writing attributes into virtual parts and committing blocks in keeper

## shared\_merge\_tree\_enable\_outdated\_parts\_check[​](#shared_merge_tree_enable_outdated_parts_check "Direct link to shared_merge_tree_enable_outdated_parts_check")

Enable outdated parts check. Only available in ClickHouse Cloud

## shared\_merge\_tree\_idle\_parts\_update\_seconds[​](#shared_merge_tree_idle_parts_update_seconds "Direct link to shared_merge_tree_idle_parts_update_seconds")

Interval in seconds for parts update without being triggered by ZooKeeper
watch in the shared merge tree. Only available in ClickHouse Cloud

## shared\_merge\_tree\_initial\_parts\_update\_backoff\_ms[​](#shared_merge_tree_initial_parts_update_backoff_ms "Direct link to shared_merge_tree_initial_parts_update_backoff_ms")

Initial backoff for parts update. Only available in ClickHouse Cloud

## shared\_merge\_tree\_interserver\_http\_connection\_timeout\_ms[​](#shared_merge_tree_interserver_http_connection_timeout_ms "Direct link to shared_merge_tree_interserver_http_connection_timeout_ms")

Timeouts for interserver HTTP connection. Only available in ClickHouse Cloud

## shared\_merge\_tree\_interserver\_http\_timeout\_ms[​](#shared_merge_tree_interserver_http_timeout_ms "Direct link to shared_merge_tree_interserver_http_timeout_ms")

Timeouts for interserver HTTP communication. Only available in ClickHouse
Cloud

## shared\_merge\_tree\_leader\_update\_period\_random\_add\_seconds[​](#shared_merge_tree_leader_update_period_random_add_seconds "Direct link to shared_merge_tree_leader_update_period_random_add_seconds")

Add uniformly distributed value from 0 to x seconds to
shared\_merge\_tree\_leader\_update\_period to avoid thundering
herd effect. Only available in ClickHouse Cloud

## shared\_merge\_tree\_leader\_update\_period\_seconds[​](#shared_merge_tree_leader_update_period_seconds "Direct link to shared_merge_tree_leader_update_period_seconds")