ClickHouse/docs/en/operations/server_settings/settings.md

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# Server settings
<a name="server_settings-builtin_dictionaries_reload_interval"></a>
## builtin_dictionaries_reload_interval
The interval in seconds before reloading built-in dictionaries.
ClickHouse reloads built-in dictionaries every x seconds. This makes it possible to edit dictionaries "on the fly" without restarting the server.
Default value: 3600.
**Example**
```xml
<builtin_dictionaries_reload_interval>3600</builtin_dictionaries_reload_interval>
```
<a name="server_settings-compression"></a>
## compression
Data compression settings.
WIP on documentation (#2692) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype * s/formats\/interfaces/interfaces\/formats/g * Remove extra clarification from header as it was too verbose, probably making it a bit more confusing * Empty article was supposed to be hidden * At least change incorrect title * Move special links to the bottom of nav and slightly highlight them * Skip hidden pages in bottom navigation too * Make front page of documentation to be part of Introduction * Make tables in introduction somewhat readable + move abbreviation definitions earlier * Some introduction text refactoring * Some docs introduction refactoring * Use admonitions instead of divs * Additional .gitignore * Treat .gif as images too * Clarify ToC item
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!!! warning "Warning"
Don't use it if you have just started using ClickHouse.
The configuration looks like this:
```xml
<compression>
<case>
<parameters/>
</case>
...
</compression>
```
You can configure multiple sections `<case>`.
Block field `<case>`:
- ``min_part_size`` The minimum size of a table part.
- ``min_part_size_ratio`` The ratio of the minimum size of a table part to the full size of the table.
- ``method`` Compression method. Acceptable values : ``lz4`` or ``zstd``(experimental).
ClickHouse checks ` min_part_size` and ` min_part_size_ratio` and processes the ` case` blocks that match these conditions. If none of the `<case>` matches, ClickHouse applies the `lz4` compression algorithm.
**Example**
```xml
<compression incl="clickhouse_compression">
<case>
<min_part_size>10000000000</min_part_size>
<min_part_size_ratio>0.01</min_part_size_ratio>
<method>zstd</method>
</case>
</compression>
```
<a name="server_settings-default_database"></a>
## default_database
The default database.
To get a list of databases, use the [SHOW DATABASES](../../query_language/misc.md#query_language_queries_show_databases).
**Example**
```xml
<default_database>default</default_database>
```
<a name="server_settings-default_profile"></a>
## default_profile
Default settings profile.
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Settings profiles are located in the file specified in the parameter [user_config](#server_settings-users_config).
**Example**
```xml
<default_profile>default</default_profile>
```
<a name="server_settings-dictionaries_config"></a>
## dictionaries_config
The path to the config file for external dictionaries.
Path:
- Specify the absolute path or the path relative to the server config file.
- The path can contain wildcards \* and ?.
See also "[External dictionaries](../../query_language/dicts/external_dicts.md#dicts-external_dicts)".
**Example**
```xml
<dictionaries_config>*_dictionary.xml</dictionaries_config>
```
<a name="server_settings-dictionaries_lazy_load"></a>
## dictionaries_lazy_load
Lazy loading of dictionaries.
If ` true`, then each dictionary is created on first use. If dictionary creation failed, the function that was using the dictionary throws an exception.
If `false`, all dictionaries are created when the server starts, and if there is an error, the server shuts down.
The default is ` true`.
**Example**
```xml
<dictionaries_lazy_load>true</dictionaries_lazy_load>
```
<a name="server_settings-format_schema_path"></a>
## format_schema_path
The path to the directory with the schemes for the input data, such as schemas for the [CapnProto](../../interfaces/formats.md#format_capnproto) format.
**Example**
```xml
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<!-- Directory containing schema files for various input formats. -->
<format_schema_path>format_schemas/</format_schema_path>
```
<a name="server_settings-graphite"></a>
## graphite
Sending data to [Graphite](https://github.com/graphite-project).
Settings:
- host The Graphite server.
- port The port on the Graphite server.
- interval The interval for sending, in seconds.
- timeout The timeout for sending data, in seconds.
- root_path Prefix for keys.
- metrics Sending data from a :ref:`system_tables-system.metrics` table.
- events Sending data from a :ref:`system_tables-system.events` table.
- asynchronous_metrics Sending data from a :ref:`system_tables-system.asynchronous_metrics` table.
You can configure multiple `<graphite>` clauses. For instance, you can use this for sending different data at different intervals.
**Example**
```xml
<graphite>
<host>localhost</host>
<port>42000</port>
<timeout>0.1</timeout>
<interval>60</interval>
<root_path>one_min</root_path>
<metrics>true</metrics>
<events>true</events>
<asynchronous_metrics>true</asynchronous_metrics>
</graphite>
```
<a name="server_settings-graphite_rollup"></a>
## graphite_rollup
Settings for thinning data for Graphite.
For more information, see [GraphiteMergeTree](../../operations/table_engines/graphitemergetree.md#table_engines-graphitemergetree).
**Example**
```xml
<graphite_rollup_example>
<default>
<function>max</function>
<retention>
<age>0</age>
<precision>60</precision>
</retention>
<retention>
<age>3600</age>
<precision>300</precision>
</retention>
<retention>
<age>86400</age>
<precision>3600</precision>
</retention>
</default>
</graphite_rollup_example>
```
<a name="server_settings-http_port"></a>
## http_port/https_port
The port for connecting to the server over HTTP(s).
If `https_port` is specified, [openSSL](#server_settings-openSSL) must be configured.
If `http_port` is specified, the openSSL configuration is ignored even if it is set.
**Example**
```xml
<https>0000</https>
```
<a name="server_settings-http_server_default_response"></a>
## http_server_default_response
The page that is shown by default when you access the ClickHouse HTTP(s) server.
**Example**
Opens `https://tabix.io/` when accessing ` http://localhost: http_port`.
```xml
<http_server_default_response>
<![CDATA[<html ng-app="SMI2"><head><base href="http://ui.tabix.io/"></head><body><div ui-view="" class="content-ui"></div><script src="http://loader.tabix.io/master.js"></script></body></html>]]>
</http_server_default_response>
```
<a name="server_settings-include_from"></a>
## include_from
The path to the file with substitutions.
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For more information, see the section "[Configuration files](../configuration_files.md#configuration_files)".
**Example**
```xml
<include_from>/etc/metrica.xml</include_from>
```
<a name="server_settings-interserver_http_port"></a>
## interserver_http_port
Port for exchanging data between ClickHouse servers.
**Example**
```xml
<interserver_http_port>9009</interserver_http_port>
```
<a name="server_settings-interserver_http_host"></a>
## interserver_http_host
The host name that can be used by other servers to access this server.
If omitted, it is defined in the same way as the ` hostname-f` command.
Useful for breaking away from a specific network interface.
**Example**
```xml
<interserver_http_host>example.yandex.ru</interserver_http_host>
```
<a name="server_settings-keep_alive_timeout"></a>
## keep_alive_timeout
The number of milliseconds that ClickHouse waits for incoming requests before closing the connection.
**Example**
```xml
<keep_alive_timeout>3</keep_alive_timeout>
```
<a name="server_settings-listen_host"></a>
## listen_host
Restriction on hosts that requests can come from. If you want the server to answer all of them, specify `::`.
Examples:
```xml
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<listen_host>::1</listen_host>
<listen_host>127.0.0.1</listen_host>
```
<a name="server_settings-logger"></a>
## logger
Logging settings.
Keys:
- level Logging level. Acceptable values: ``trace``, ``debug``, ``information``, ``warning``, ``error``.
- log The log file. Contains all the entries according to `` level``.
- errorlog Error log file.
- size Size of the file. Applies to ``log``and``errorlog``. Once the file reaches ``size``, ClickHouse archives and renames it, and creates a new log file in its place.
- count The number of archived log files that ClickHouse stores.
**Example**
```xml
<logger>
<level>trace</level>
<log>/var/log/clickhouse-server/clickhouse-server.log</log>
<errorlog>/var/log/clickhouse-server/clickhouse-server.err.log</errorlog>
<size>1000M</size>
<count>10</count>
</logger>
```
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Also, logging to syslog is possible. Configuration example:
```xml
<logger>
<use_syslog>1</use_syslog>
<syslog>
<address>syslog.remote:10514</address>
WIP on documentation (#2692) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype * s/formats\/interfaces/interfaces\/formats/g * Remove extra clarification from header as it was too verbose, probably making it a bit more confusing * Empty article was supposed to be hidden * At least change incorrect title * Move special links to the bottom of nav and slightly highlight them * Skip hidden pages in bottom navigation too * Make front page of documentation to be part of Introduction * Make tables in introduction somewhat readable + move abbreviation definitions earlier * Some introduction text refactoring * Some docs introduction refactoring * Use admonitions instead of divs * Additional .gitignore * Treat .gif as images too * Clarify ToC item
2018-07-20 17:35:34 +00:00
<hostname>myhost.local</hostname>
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<facility>LOG_LOCAL6</facility>
<format>syslog</format>
</syslog>
</logger>
```
Keys:
- user_syslog - activation key, turning on syslog logging.
- address - host[:port] of syslogd. If not specified, local one would be used.
- hostname - optional, source host of logs
WIP on documentation (#2692) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype * s/formats\/interfaces/interfaces\/formats/g * Remove extra clarification from header as it was too verbose, probably making it a bit more confusing * Empty article was supposed to be hidden * At least change incorrect title * Move special links to the bottom of nav and slightly highlight them * Skip hidden pages in bottom navigation too * Make front page of documentation to be part of Introduction * Make tables in introduction somewhat readable + move abbreviation definitions earlier * Some introduction text refactoring * Some docs introduction refactoring * Use admonitions instead of divs * Additional .gitignore * Treat .gif as images too * Clarify ToC item
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- facility - [syslog facility](https://en.wikipedia.org/wiki/Syslog#Facility),
in uppercase, prefixed with "LOG_": (``LOG_USER``, ``LOG_DAEMON``, ``LOG_LOCAL3`` etc.).
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Default values: when ``address`` is specified, then ``LOG_USER``, otherwise - ``LOG_DAEMON``
- format - message format. Possible values are - ``bsd`` and ``syslog``
<a name="server_settings-macros"></a>
## macros
Parameter substitutions for replicated tables.
Can be omitted if replicated tables are not used.
For more information, see the section "[Creating replicated tables](../../operations/table_engines/replication.md#table_engines-replication-creation_of_rep_tables)".
**Example**
```xml
<macros incl="macros" optional="true" />
```
<a name="server_settings-mark_cache_size"></a>
## mark_cache_size
Approximate size (in bytes) of the cache of "marks" used by [MergeTree](../../operations/table_engines/mergetree.md#table_engines-mergetree) engines.
The cache is shared for the server and memory is allocated as needed. The cache size must be at least 5368709120.
**Example**
```xml
<mark_cache_size>5368709120</mark_cache_size>
```
<a name="server_settings-max_concurrent_queries"></a>
## max_concurrent_queries
The maximum number of simultaneously processed requests.
**Example**
```xml
<max_concurrent_queries>100</max_concurrent_queries>
```
<a name="server_settings-max_connections"></a>
## max_connections
The maximum number of inbound connections.
**Example**
```xml
<max_connections>4096</max_connections>
```
<a name="server_settings-max_open_files"></a>
## max_open_files
The maximum number of open files.
By default: `maximum`.
We recommend using this option in Mac OS X, since the ` getrlimit()` function returns an incorrect value.
**Example**
```xml
<max_open_files>262144</max_open_files>
```
<a name="server_settings-max_table_size_to_drop"></a>
## max_table_size_to_drop
Restriction on deleting tables.
If the size of a [MergeTree](../../operations/table_engines/mergetree.md#table_engines-mergetree) type table exceeds `max_table_size_to_drop` (in bytes), you can't delete it using a DROP query.
If you still need to delete the table without restarting the ClickHouse server, create the ` <clickhouse-path>/flags/force_drop_table` file and run the DROP query.
Default value: 50 GB.
The value 0 means that you can delete all tables without any restrictions.
**Example**
```xml
<max_table_size_to_drop>0</max_table_size_to_drop>
```
<a name="server_settings-merge_tree"></a>
## merge_tree
Fine tuning for tables in the [ MergeTree](../../operations/table_engines/mergetree.md#table_engines-mergetree) family.
For more information, see the MergeTreeSettings.h header file.
**Example**
```xml
<merge_tree>
<max_suspicious_broken_parts>5</max_suspicious_broken_parts>
</merge_tree>
```
<a name="server_settings-openSSL"></a>
## openSSL
SSL client/server configuration.
Support for SSL is provided by the `` libpoco`` library. The interface is described in the file [SSLManager.h](https://github.com/ClickHouse-Extras/poco/blob/master/NetSSL_OpenSSL/include/Poco/Net/SSLManager.h)
Keys for server/client settings:
- privateKeyFile The path to the file with the secret key of the PEM certificate. The file may contain a key and certificate at the same time.
- certificateFile The path to the client/server certificate file in PEM format. You can omit it if `` privateKeyFile`` contains the certificate.
- caConfig The path to the file or directory that contains trusted root certificates.
- verificationMode The method for checking the node's certificates. Details are in the description of the [Context](https://github.com/ClickHouse-Extras/poco/blob/master/NetSSL_OpenSSL/include/Poco/Net/Context.h) class. Possible values: ``none``, ``relaxed``, ``strict``, ``once``.
- verificationDepth The maximum length of the verification chain. Verification will fail if the certificate chain length exceeds the set value.
- loadDefaultCAFile Indicates that built-in CA certificates for OpenSSL will be used. Acceptable values: `` true``, `` false``. |
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- cipherList Supported OpenSSL encryptions. For example: `` ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH``.
- cacheSessions Enables or disables caching sessions. Must be used in combination with ``sessionIdContext``. Acceptable values: `` true``, `` false``.
- sessionIdContext A unique set of random characters that the server appends to each generated identifier. The length of the string must not exceed ``SSL_MAX_SSL_SESSION_ID_LENGTH``. This parameter is always recommended, since it helps avoid problems both if the server caches the session and if the client requested caching. Default value: ``${application.name}``.
- sessionCacheSize The maximum number of sessions that the server caches. Default value: 1024\*20. 0 Unlimited sessions.
- sessionTimeout Time for caching the session on the server.
- extendedVerification Automatically extended verification of certificates after the session ends. Acceptable values: `` true``, `` false``.
- requireTLSv1 Require a TLSv1 connection. Acceptable values: `` true``, `` false``.
- requireTLSv1_1 Require a TLSv1.1 connection. Acceptable values: `` true``, `` false``.
- requireTLSv1 Require a TLSv1.2 connection. Acceptable values: `` true``, `` false``.
- fips Activates OpenSSL FIPS mode. Supported if the library's OpenSSL version supports FIPS.
- privateKeyPassphraseHandler Class (PrivateKeyPassphraseHandler subclass) that requests the passphrase for accessing the private key. For example: ``<privateKeyPassphraseHandler>``, ``<name>KeyFileHandler</name>``, ``<options><password>test</password></options>``, ``</privateKeyPassphraseHandler>``.
- invalidCertificateHandler Class (subclass of CertificateHandler) for verifying invalid certificates. For example: `` <invalidCertificateHandler> <name>ConsoleCertificateHandler</name> </invalidCertificateHandler>`` .
- disableProtocols Protocols that are not allowed to use.
- preferServerCiphers Preferred server ciphers on the client.
**Example of settings:**
```xml
<openSSL>
<server>
<!-- openssl req -subj "/CN=localhost" -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout /etc/clickhouse-server/server.key -out /etc/clickhouse-server/server.crt -->
<certificateFile>/etc/clickhouse-server/server.crt</certificateFile>
<privateKeyFile>/etc/clickhouse-server/server.key</privateKeyFile>
<!-- openssl dhparam -out /etc/clickhouse-server/dhparam.pem 4096 -->
<dhParamsFile>/etc/clickhouse-server/dhparam.pem</dhParamsFile>
<verificationMode>none</verificationMode>
<loadDefaultCAFile>true</loadDefaultCAFile>
<cacheSessions>true</cacheSessions>
<disableProtocols>sslv2,sslv3</disableProtocols>
<preferServerCiphers>true</preferServerCiphers>
</server>
<client>
<loadDefaultCAFile>true</loadDefaultCAFile>
<cacheSessions>true</cacheSessions>
<disableProtocols>sslv2,sslv3</disableProtocols>
<preferServerCiphers>true</preferServerCiphers>
<!-- Use for self-signed: <verificationMode>none</verificationMode> -->
<invalidCertificateHandler>
<!-- Use for self-signed: <name>AcceptCertificateHandler</name> -->
<name>RejectCertificateHandler</name>
</invalidCertificateHandler>
</client>
</openSSL>
```
<a name="server_settings-part_log"></a>
## part_log
Logging events that are associated with [MergeTree](../../operations/table_engines/mergetree.md#table_engines-mergetree) data. For instance, adding or merging data. You can use the log to simulate merge algorithms and compare their characteristics. You can visualize the merge process.
Queries are logged in the ClickHouse table, not in a separate file.
Columns in the log:
- event_time Date of the event.
- duration_ms Duration of the event.
- event_type Type of event. 1 new data part; 2 merge result; 3 data part downloaded from replica; 4 data part deleted.
- database_name The name of the database.
- table_name Name of the table.
- part_name Name of the data part.
- size_in_bytes Size of the data part in bytes.
- merged_from An array of names of data parts that make up the merge (also used when downloading a merged part).
- merge_time_ms Time spent on the merge.
Use the following parameters to configure logging:
- database Name of the database.
- table Name of the table.
- partition_by Sets a [custom partitioning key](../../operations/table_engines/custom_partitioning_key.md#custom-partitioning-key).
- flush_interval_milliseconds Interval for flushing data from memory to the disk.
**Example**
```xml
<part_log>
<database>system</database>
<table>part_log</table>
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<partition_by>toMonday(event_date)</partition_by>
<flush_interval_milliseconds>7500</flush_interval_milliseconds>
</part_log>
```
<a name="server_settings-path"></a>
## path
The path to the directory containing data.
WIP on documentation (#2692) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype * s/formats\/interfaces/interfaces\/formats/g * Remove extra clarification from header as it was too verbose, probably making it a bit more confusing * Empty article was supposed to be hidden * At least change incorrect title * Move special links to the bottom of nav and slightly highlight them * Skip hidden pages in bottom navigation too * Make front page of documentation to be part of Introduction * Make tables in introduction somewhat readable + move abbreviation definitions earlier * Some introduction text refactoring * Some docs introduction refactoring * Use admonitions instead of divs * Additional .gitignore * Treat .gif as images too * Clarify ToC item
2018-07-20 17:35:34 +00:00
!!! warning "Attention"
The trailing slash is mandatory.
**Example**
```xml
<path>/var/lib/clickhouse/</path>
```
<a name="server_settings-query_log"></a>
## query_log
Setting for logging queries received with the [log_queries=1](../settings/settings.md#settings_settings-log_queries) setting.
Queries are logged in the ClickHouse table, not in a separate file.
Use the following parameters to configure logging:
- database Name of the database.
- table Name of the table.
- partition_by Sets a [custom partitioning key](../../operations/table_engines/custom_partitioning_key.md#custom-partitioning-key).
- flush_interval_milliseconds Interval for flushing data from memory to the disk.
If the table doesn't exist, ClickHouse will create it. If the structure of the query log changed when the ClickHouse server was updated, the table with the old structure is renamed, and a new table is created automatically.
**Example**
```xml
<query_log>
<database>system</database>
<table>query_log</table>
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<partition_by>toMonday(event_date)</partition_by>
<flush_interval_milliseconds>7500</flush_interval_milliseconds>
</query_log>
```
<a name="server_settings-remote_servers"></a>
## remote_servers
Configuration of clusters used by the Distributed table engine.
For more information, see the section "[Table engines/Distributed](../../operations/table_engines/distributed.md#table_engines-distributed)".
**Example**
```xml
<remote_servers incl="clickhouse_remote_servers" />
```
For the value of the `incl` attribute, see the section "[Configuration files](../configuration_files.md#configuration_files)".
<a name="server_settings-timezone"></a>
## timezone
The server's time zone.
Specified as an IANA identifier for the UTC time zone or geographic location (for example, Africa/Abidjan).
The time zone is necessary for conversions between String and DateTime formats when DateTime fields are output to text format (printed on the screen or in a file), and when getting DateTime from a string. In addition, the time zone is used in functions that work with the time and date if they didn't receive the time zone in the input parameters.
**Example**
```xml
<timezone>Europe/Moscow</timezone>
```
<a name="server_settings-tcp_port"></a>
## tcp_port
Port for communicating with clients over the TCP protocol.
**Example**
```xml
<tcp_port>9000</tcp_port>
```
<a name="server_settings-tmp_path"></a>
## tmp_path
Path to temporary data for processing large queries.
WIP on documentation (#2692) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype * s/formats\/interfaces/interfaces\/formats/g * Remove extra clarification from header as it was too verbose, probably making it a bit more confusing * Empty article was supposed to be hidden * At least change incorrect title * Move special links to the bottom of nav and slightly highlight them * Skip hidden pages in bottom navigation too * Make front page of documentation to be part of Introduction * Make tables in introduction somewhat readable + move abbreviation definitions earlier * Some introduction text refactoring * Some docs introduction refactoring * Use admonitions instead of divs * Additional .gitignore * Treat .gif as images too * Clarify ToC item
2018-07-20 17:35:34 +00:00
!!! warning "Attention"
The trailing slash is mandatory.
**Example**
```xml
<tmp_path>/var/lib/clickhouse/tmp/</tmp_path>
```
<a name="server_settings-uncompressed_cache_size"></a>
## uncompressed_cache_size
Cache size (in bytes) for uncompressed data used by table engines from the [MergeTree](../../operations/table_engines/mergetree.md#table_engines-mergetree) family.
There is one shared cache for the server. Memory is allocated on demand. The cache is used if the option [use_uncompressed_cache](../settings/settings.md#settings-use_uncompressed_cache) is enabled.
The uncompressed cache is advantageous for very short queries in individual cases.
**Example**
```xml
<uncompressed_cache_size>8589934592</uncompressed_cache_size>
```
## user_files_path
A catalog with user files. Used in a [file()](../../query_language/table_functions/file.md#table_functions-file) table function.
**Example**
```xml
<user_files_path>/var/lib/clickhouse/user_files/</user_files_path>
```
<a name="server_settings-users_config"></a>
## users_config
Path to the file that contains:
- User configurations.
- Access rights.
- Settings profiles.
- Quota settings.
**Example**
```xml
<users_config>users.xml</users_config>
```
<a name="server_settings-zookeeper"></a>
## zookeeper
Configuration of ZooKeeper servers.
ClickHouse uses ZooKeeper for storing replica metadata when using replicated tables.
This parameter can be omitted if replicated tables are not used.
For more information, see the section "[Replication](../../operations/table_engines/replication.md#table_engines-replication)".
**Example**
```xml
<zookeeper incl="zookeeper-servers" optional="true" />
```