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67 lines
7.3 KiB
Markdown
67 lines
7.3 KiB
Markdown
---
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slug: /en/operations/system-tables/server_settings
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---
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# server_settings
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Contains information about global settings for the server, which were specified in `config.xml`.
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Currently, the table shows only settings from the first layer of `config.xml` and doesn't support nested configs (e.g. [logger](../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-logger)).
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Columns:
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- `name` ([String](../../sql-reference/data-types/string.md)) — Server setting name.
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- `value` ([String](../../sql-reference/data-types/string.md)) — Server setting value.
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- `default` ([String](../../sql-reference/data-types/string.md)) — Server setting default value.
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- `changed` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Shows whether a setting was specified in `config.xml`
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- `description` ([String](../../sql-reference/data-types/string.md)) — Short server setting description.
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- `type` ([String](../../sql-reference/data-types/string.md)) — Server setting value type.
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- `changeable_without_restart` ([Enum8](../../sql-reference/data-types/enum.md)) — Whether the setting can be changed at server runtime. Values:
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- `'No' `
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- `'IncreaseOnly'`
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- `'DecreaseOnly'`
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- `'Yes'`
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- `is_obsolete` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) - Shows whether a setting is obsolete.
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**Example**
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The following example shows how to get information about server settings which name contains `thread_pool`.
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``` sql
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SELECT *
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FROM system.server_settings
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WHERE name LIKE '%thread_pool%'
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```
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``` text
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┌─name──────────────────────────────────────────┬─value─┬─default─┬─changed─┬─description─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬─type───┬─changeable_without_restart─┬─is_obsolete─┐
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│ max_thread_pool_size │ 10000 │ 10000 │ 0 │ The maximum number of threads that could be allocated from the OS and used for query execution and background operations. │ UInt64 │ No │ 0 │
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│ max_thread_pool_free_size │ 1000 │ 1000 │ 0 │ The maximum number of threads that will always stay in a global thread pool once allocated and remain idle in case of insufficient number of tasks. │ UInt64 │ No │ 0 │
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│ thread_pool_queue_size │ 10000 │ 10000 │ 0 │ The maximum number of tasks that will be placed in a queue and wait for execution. │ UInt64 │ No │ 0 │
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│ max_io_thread_pool_size │ 100 │ 100 │ 0 │ The maximum number of threads that would be used for IO operations │ UInt64 │ No │ 0 │
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│ max_io_thread_pool_free_size │ 0 │ 0 │ 0 │ Max free size for IO thread pool. │ UInt64 │ No │ 0 │
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│ io_thread_pool_queue_size │ 10000 │ 10000 │ 0 │ Queue size for IO thread pool. │ UInt64 │ No │ 0 │
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│ max_active_parts_loading_thread_pool_size │ 64 │ 64 │ 0 │ The number of threads to load active set of data parts (Active ones) at startup. │ UInt64 │ No │ 0 │
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│ max_outdated_parts_loading_thread_pool_size │ 32 │ 32 │ 0 │ The number of threads to load inactive set of data parts (Outdated ones) at startup. │ UInt64 │ No │ 0 │
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│ max_unexpected_parts_loading_thread_pool_size │ 32 │ 32 │ 0 │ The number of threads to load inactive set of data parts (Unexpected ones) at startup. │ UInt64 │ No │ 0 │
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│ max_parts_cleaning_thread_pool_size │ 128 │ 128 │ 0 │ The number of threads for concurrent removal of inactive data parts. │ UInt64 │ No │ 0 │
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│ max_backups_io_thread_pool_size │ 1000 │ 1000 │ 0 │ The maximum number of threads that would be used for IO operations for BACKUP queries │ UInt64 │ No │ 0 │
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│ max_backups_io_thread_pool_free_size │ 0 │ 0 │ 0 │ Max free size for backups IO thread pool. │ UInt64 │ No │ 0 │
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│ backups_io_thread_pool_queue_size │ 0 │ 0 │ 0 │ Queue size for backups IO thread pool. │ UInt64 │ No │ 0 │
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└───────────────────────────────────────────────┴───────┴─────────┴─────────┴─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴────────┴────────────────────────────┴─────────────┘
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```
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Using of `WHERE changed` can be useful, for example, when you want to check
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whether settings in configuration files are loaded correctly and are in use.
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<!-- -->
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``` sql
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SELECT * FROM system.server_settings WHERE changed AND name='max_thread_pool_size'
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```
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**See also**
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- [Settings](../../operations/system-tables/settings.md)
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- [Configuration Files](../../operations/configuration-files.md)
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- [Server Settings](../../operations/server-configuration-parameters/settings.md)
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