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56 lines
4.6 KiB
Markdown
56 lines
4.6 KiB
Markdown
---
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machine_translated: true
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machine_translated_rev: 5decc73b5dc60054f19087d3690c4eb99446a6c3
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---
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# 系统。设置 {#system-tables-system-settings}
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包含有关当前用户的会话设置的信息。
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列:
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- `name` ([字符串](../../sql-reference/data-types/string.md)) — Setting name.
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- `value` ([字符串](../../sql-reference/data-types/string.md)) — Setting value.
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- `changed` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Shows whether a setting is changed from its default value.
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- `description` ([字符串](../../sql-reference/data-types/string.md)) — Short setting description.
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- `min` ([可为空](../../sql-reference/data-types/nullable.md)([字符串](../../sql-reference/data-types/string.md))) — Minimum value of the setting, if any is set via [制约因素](../../operations/settings/constraints-on-settings.md#constraints-on-settings). 如果设置没有最小值，则包含 [NULL](../../sql-reference/syntax.md#null-literal).
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- `max` ([可为空](../../sql-reference/data-types/nullable.md)([字符串](../../sql-reference/data-types/string.md))) — Maximum value of the setting, if any is set via [制约因素](../../operations/settings/constraints-on-settings.md#constraints-on-settings). 如果设置没有最大值，则包含 [NULL](../../sql-reference/syntax.md#null-literal).
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- `readonly` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Shows whether the current user can change the setting:
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- `0` — Current user can change the setting.
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- `1` — Current user can't change the setting.
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**示例**
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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`.
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``` sql
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SELECT *
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FROM system.settings
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WHERE name LIKE '%min_i%'
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```
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``` text
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┌─name────────────────────────────────────────┬─value─────┬─changed─┬─description───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬─min──┬─max──┬─readonly─┐
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│ 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 │
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│ 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 │
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│ 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 │
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└─────────────────────────────────────────────┴───────────┴─────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴──────┴──────┴──────────┘
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```
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使用 `WHERE changed` 可以是有用的，例如，当你想检查:
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- 配置文件中的设置是否正确加载并正在使用。
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- 在当前会话中更改的设置。
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<!-- -->
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``` sql
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SELECT * FROM system.settings WHERE changed AND name='load_balancing'
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```
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**另请参阅**
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- [设置](../../operations/settings/index.md#session-settings-intro)
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- [查询权限](../../operations/settings/permissions-for-queries.md#settings_readonly)
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- [对设置的限制](../../operations/settings/constraints-on-settings.md)
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