ClickHouse/docs/zh/operations/system-tables/settings.md

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系统。设置

包含有关当前用户的会话设置的信息。

列:

• name (字符串) — Setting name.
• value (字符串) — Setting value.
• changed (UInt8) — Shows whether a setting is changed from its default value.
• description (字符串) — Short setting description.
• min (可为空(字符串)) — Minimum value of the setting, if any is set via 制约因素. 如果设置没有最小值，则包含 NULL.
• max (可为空(字符串)) — Maximum value of the setting, if any is set via 制约因素. 如果设置没有最大值，则包含 NULL.
• readonly (UInt8) — Shows whether the current user can change the setting:
  • 0 — Current user can change the setting.
  • 1 — Current user can't change the setting.

示例

下面的示例演示如何获取有关名称包含的设置的信息 min_i.

SELECT *
FROM system.settings
WHERE name LIKE '%min_i%'

┌─name────────────────────────────────────────┬─value─────┬─changed─┬─description───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬─min──┬─max──┬─readonly─┐
│ min_insert_block_size_rows                  │ 1048576   │       0 │ Squash blocks passed to INSERT query to specified size in rows, if blocks are not big enough.                                                                         │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │        0 │
│ min_insert_block_size_bytes                 │ 268435456 │       0 │ Squash blocks passed to INSERT query to specified size in bytes, if blocks are not big enough.                                                                        │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │        0 │
│ read_backoff_min_interval_between_events_ms │ 1000      │       0 │ Settings to reduce the number of threads in case of slow reads. Do not pay attention to the event, if the previous one has passed less than a certain amount of time. │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │        0 │
└─────────────────────────────────────────────┴───────────┴─────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴──────┴──────┴──────────┘

使用 WHERE changed 可以是有用的，例如，当你想检查:

• 配置文件中的设置是否正确加载并正在使用。
• 在当前会话中更改的设置。

SELECT * FROM system.settings WHERE changed AND name='load_balancing'

另请参阅

• 设置
• 查询权限
• 对设置的限制