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server_settings

包含有关服务器全局设置的信息,这些设置是在 config.xml 中指定的。目前,该表仅显示 config.xml 第一层级的设置,不支持嵌套配置(例如 logger)。

  • name (字符串) — 服务器设置名称。
  • value (字符串) — 服务器设置值。
  • default (字符串) — 服务器设置默认值。
  • changed (UInt8) — 显示设置是否在 config.xml 中指定。
  • description (字符串) — 简短的服务器设置描述。
  • type (字符串) — 服务器设置值类型。
  • changeable_without_restart (Enum8) — 设置是否可以在服务器运行时更改。值
    • '否'
    • '仅增'
    • '仅减'
    • '是'
  • is_obsolete (UInt8) - 显示设置是否已过时。

示例

以下示例显示如何获取名称包含 thread_pool 的服务器设置信息。

SELECT *
FROM system.server_settings
WHERE name LIKE '%thread_pool%'
┌─name──────────────────────────────────────────┬─value─┬─default─┬─changed─┬─description─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬─type───┬─changeable_without_restart─┬─is_obsolete─┐
│ 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 │
│ 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 │
│ 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 │
│ max_io_thread_pool_size │ 100 │ 100 │ 0 │ The maximum number of threads that would be used for IO operations │ UInt64 │ No │ 0 │
│ max_io_thread_pool_free_size │ 0 │ 0 │ 0 │ Max free size for IO thread pool. │ UInt64 │ No │ 0 │
│ io_thread_pool_queue_size │ 10000 │ 10000 │ 0 │ Queue size for IO thread pool. │ UInt64 │ No │ 0 │
│ 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 │
│ max_outdated_parts_loading_thread_pool_size │ 32 │ 32 │ 0 │ The number of threads to load inactive set of data parts (Outdated ones) at startup.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 │
│ 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 │
│ max_parts_cleaning_thread_pool_size │ 128 │ 128 │ 0 │ The number of threads for concurrent removal of inactive data parts. │ UInt64 │ No │ 0 │
│ 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 │
│ max_backups_io_thread_pool_free_size │ 0 │ 0 │ 0 │ Max free size for backups IO thread pool. │ UInt64 │ No │ 0 │
│ backups_io_thread_pool_queue_size │ 0 │ 0 │ 0 │ Queue size for backups IO thread pool. │ UInt64 │ No │ 0 │
└───────────────────────────────────────────────┴───────┴─────────┴─────────┴─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴────────┴────────────────────────────┴─────────────┘

使用 WHERE changed 非常有用,例如,当您想检查配置文件中的设置是否已正确加载并正在使用时。

SELECT * FROM system.server_settings WHERE changed AND name='max_thread_pool_size'

另请参阅