Server Settings

## parts\_kill\_delay\_period[​](#parts_kill_delay_period "Direct link to parts_kill_delay_period")

Period to completely remove parts for SharedMergeTree. Only available in ClickHouse Cloud

## parts\_kill\_delay\_period\_random\_add[​](#parts_kill_delay_period_random_add "Direct link to parts_kill_delay_period_random_add")

Add uniformly distributed value from 0 to x seconds to kill\_delay\_period to avoid thundering herd effect and subsequent DoS of ZooKeeper in case of very large number of tables. Only available in ClickHouse Cloud

## parts\_killer\_pool\_size[​](#parts_killer_pool_size "Direct link to parts_killer_pool_size")

Threads for cleanup of shared merge tree parts killer threads. Only available in ClickHouse Cloud

## path[​](#path "Direct link to path")

The path to the directory containing data.

Note

The trailing slash is mandatory.

**Example**

```
<path>/var/lib/clickhouse/</path>
```

## postgresql\_port[​](#postgresql_port "Direct link to postgresql_port")

Port for communicating with clients over PostgreSQL protocol.

Note

- Positive integers specify the port number to listen to
- Empty values are used to disable communication with clients over PostgreSQL protocol.

**Example**

```
<postgresql_port>9005</postgresql_port>
```

## postgresql\_require\_secure\_transport[​](#postgresql_require_secure_transport "Direct link to postgresql_require_secure_transport")

If set to true, secure communication is required with clients over [postgresql\_port](/docs/operations/server-configuration-parameters/settings#postgresql_port). Connection with option `<sslmode=disable>` will be refused. Use it with [OpenSSL](/docs/operations/server-configuration-parameters/settings#openssl) settings.

## prefetch\_threadpool\_pool\_size[​](#prefetch_threadpool_pool_size "Direct link to prefetch_threadpool_pool_size")

Size of background pool for prefetches for remote object storages

## prefetch\_threadpool\_queue\_size[​](#prefetch_threadpool_queue_size "Direct link to prefetch_threadpool_queue_size")

Number of tasks which is possible to push into prefetches pool

## prefixes\_deserialization\_thread\_pool\_thread\_pool\_queue\_size[​](#prefixes_deserialization_thread_pool_thread_pool_queue_size "Direct link to prefixes_deserialization_thread_pool_thread_pool_queue_size")

The maximum number of jobs that can be scheduled on the prefixes deserialization Thread pool.

Note

A value of `0` means unlimited.

## prepare\_system\_log\_tables\_on\_startup[​](#prepare_system_log_tables_on_startup "Direct link to prepare_system_log_tables_on_startup")

If true, ClickHouse creates all configured `system.*_log` tables before the startup. It can be helpful if some startup scripts depend on these tables.

## primary\_index\_cache\_policy[​](#primary_index_cache_policy "Direct link to primary_index_cache_policy")

Primary index cache policy name.

## primary\_index\_cache\_prewarm\_ratio[​](#primary_index_cache_prewarm_ratio "Direct link to primary_index_cache_prewarm_ratio")

The ratio of total size of mark cache to fill during prewarm.

## primary\_index\_cache\_size[​](#primary_index_cache_size "Direct link to primary_index_cache_size")

Maximum size of cache for primary index (index of MergeTree family of tables).

## primary\_index\_cache\_size\_ratio[​](#primary_index_cache_size_ratio "Direct link to primary_index_cache_size_ratio")

The size of the protected queue (in case of SLRU policy) in the primary index cache relative to the cache's total size.

## process\_query\_plan\_packet[​](#process_query_plan_packet "Direct link to process_query_plan_packet")

This setting allows reading QueryPlan packet. This packet is sent for distributed queries when serialize\_query\_plan is enabled.
Disabled by default to avoid possible security issues which can be caused by bugs in query plan binary deserialization.

**Example**

```
<process_query_plan_packet>true</process_query_plan_packet>
```

## processors\_profile\_log[​](#processors_profile_log "Direct link to processors_profile_log")

Settings for the [`processors_profile_log`](/docs/operations/system-tables/processors_profile_log) system table.

The following settings can be configured by sub-tags: