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* prefer relative links from root * wip * split aggregate function reference * split system tables
51 lines
4.5 KiB
Markdown
51 lines
4.5 KiB
Markdown
# system.settings {#system-tables-system-settings}
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Contains information about session settings for current user.
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Columns:
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- `name` ([String](../../sql-reference/data-types/string.md)) — Setting name.
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- `value` ([String](../../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` ([String](../../sql-reference/data-types/string.md)) — Short setting description.
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- `min` ([Nullable](../../sql-reference/data-types/nullable.md)([String](../../sql-reference/data-types/string.md))) — Minimum value of the setting, if any is set via [constraints](../../operations/settings/constraints-on-settings.md#constraints-on-settings). If the setting has no minimum value, contains [NULL](../../sql-reference/syntax.md#null-literal).
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- `max` ([Nullable](../../sql-reference/data-types/nullable.md)([String](../../sql-reference/data-types/string.md))) — Maximum value of the setting, if any is set via [constraints](../../operations/settings/constraints-on-settings.md#constraints-on-settings). If the setting has no maximum value, contains [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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**Example**
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The following example shows how to get information about settings which name contains `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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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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- Settings that changed in the current session.
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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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**See also**
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- [Settings](../../operations/settings/index.md#session-settings-intro)
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- [Permissions for Queries](../../operations/settings/permissions-for-queries.md#settings_readonly)
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- [Constraints on Settings](../../operations/settings/constraints-on-settings.md)
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