max_active_parts_loading_thread_pool_size
The number of threads to load active set of data parts (Active ones) at startup.max_authentication_methods_per_user
The maximum number of authentication methods a user can be created with or altered to. Changing this setting does not affect existing users. Create/alter authentication-related queries will fail if they exceed the limit specified in this setting. Non authentication create/alter queries will succeed.A value of
0 means unlimited.max_backup_bandwidth_for_server
The maximum read speed in bytes per second for all backups on server. Zero means unlimited.max_build_vector_similarity_index_thread_pool_size
The maximum number of threads to use for building vector indexes.A value of
0 means all cores.max_connections
Max server connections.max_entries_for_hash_table_stats
How many entries hash table statistics collected during aggregation is allowed to havemax_fetch_partition_thread_pool_size
The number of threads for ALTER TABLE FETCH PARTITION.max_held_snapshots
Maximum number of lightweight snapshots that can be held at the same time. Zero means unlimited. If the number of snapshots reaches this limit, an exception is thrown when trying to create a new snapshot.max_http_index_page_size
Maximum size of an HTTP index page response used for directory listing over HTTP. If the response exceeds this limit, the query fails with an error. Default:10485760 (10 MiB).
max_keep_alive_requests
Maximal number of requests through a single keep-alive connection until it will be closed by ClickHouse server. Examplemax_materialized_views_count_for_table
A limit on the number of materialized views attached to a table.Only directly dependent views are considered here, and the creation of one view on top of another view is not considered.
max_merges_bandwidth_for_server
The maximum read speed of all merges on server in bytes per second. Zero means unlimited.max_mutations_bandwidth_for_server
The maximum read speed of all mutations on server in bytes per second. Zero means unlimited.max_open_files
The maximum number of open files.We recommend using this option in macOS since the getrlimit() function returns an incorrect value.
max_os_cpu_wait_time_ratio_to_drop_connection
Max ratio between OS CPU wait (OSCPUWaitMicroseconds metric) and busy (OSCPUVirtualTimeMicroseconds metric) times to consider dropping connections. Linear interpolation between min and max ratio is used to calculate the probability, the probability is 1 at this point. See Controlling behavior on server CPU overload for more details.max_outdated_parts_loading_thread_pool_size
The number of threads to load inactive set of data parts (Outdated ones) at startup.max_part_num_to_warn
If the number of active parts exceeds the specified value, clickhouse server will add warning messages tosystem.warnings table.
Example
max_partition_size_to_drop
Restriction on dropping partitions. If the size of a MergeTree table exceedsmax_partition_size_to_drop (in bytes), you can’t drop a partition using a DROP PARTITION query.
This setting does not require a restart of the ClickHouse server to apply. Another way to disable the restriction is to create the <clickhouse-path>/flags/force_drop_table file.
The value
0 means that you can drop partitions without any restrictions.This limitation does not restrict drop table and truncate table, see max_table_size_to_dropmax_parts_cleaning_thread_pool_size
The number of threads for concurrent removal of inactive data parts.max_per_cpu_untracked_memory
Upper bound, in bytes, on the untracked memory all threads running on one CPU may hold at once before it is flushed to the memory tracker. Whilemax_untracked_memory bounds a single thread, this bounds the per-CPU total, so many threads cannot multiply their per-thread allowance into a large server-wide overcommit. The total untracked memory is therefore bounded by roughly number_of_cpus * max_per_cpu_untracked_memory. A value of 0 disables the per-CPU bound (only the per-thread max_untracked_memory applies). Linux only.
max_session_timeout
Maximum session timeout, in seconds. Example:max_temporary_data_on_disk_size
The maximum amount of storage that could be used for external aggregation, joins or sorting. Queries that exceed this limit will fail with an exception.A value of
0 means unlimited.max_unexpected_parts_loading_thread_pool_size
The number of threads to load inactive set of data parts (Unexpected ones) at startup.max_waiting_queries
Limit on total number of concurrently waiting queries. Execution of a waiting query is blocked while required tables are loading asynchronously (seeasync_load_databases.
Waiting queries are not counted when limits controlled by the following settings are checked:
max_concurrent_queriesmax_concurrent_insert_queriesmax_concurrent_select_queriesmax_concurrent_queries_for_usermax_concurrent_queries_for_all_users
A value of
0 (default) means unlimited.This setting can be modified at runtime and will take effect immediately. Queries that are already running will remain unchanged.max_zookeeper_pooled_connections
Maximum number of lazily initialized ZooKeeper sessions per ZooKeeper cluster in the shared pool. A value of0 disables pooled connections and keeps using a single session.