mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-09-29 13:10:48 +00:00
51 lines
4.5 KiB
Markdown
51 lines
4.5 KiB
Markdown
|
# system.settings {#system-tables-system-settings}
|
|||
|
|
|
|||
|
|
Contains information about session settings for current user.
|
|||
|
|
|
|||
|
|
Columns:
|
|||
|
|
|
|||
|
|
- `name` ([String](../../sql-reference/data-types/string.md)) — Setting name.
|
|||
|
|
- `value` ([String](../../sql-reference/data-types/string.md)) — Setting value.
|
|||
|
|
- `changed` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Shows whether a setting is changed from its default value.
|
|||
|
|
- `description` ([String](../../sql-reference/data-types/string.md)) — Short setting description.
|
|||
|
|
- `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).
|
|||
|
|
- `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).
|
|||
|
|
- `readonly` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Shows whether the current user can change the setting:
|
|||
|
|
- `0` — Current user can change the setting.
|
|||
|
|
- `1` — Current user can’t change the setting.
|
|||
|
|
|
|||
|
|
**Example**
|
|||
|
|
|
|||
|
|
The following example shows how to get information about settings which name contains `min_i`.
|
|||
|
|
|
|||
|
|
``` sql
|
|||
|
|
SELECT *
|
|||
|
|
FROM system.settings
|
|||
|
|
WHERE name LIKE '%min_i%'
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
``` text
|
|||
|
|
┌─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 │
|
|||
|
|
└─────────────────────────────────────────────┴───────────┴─────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴──────┴──────┴──────────┘
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
Using of `WHERE changed` can be useful, for example, when you want to check:
|
|||
|
|
|
|||
|
|
- Whether settings in configuration files are loaded correctly and are in use.
|
|||
|
|
- Settings that changed in the current session.
|
|||
|
|
|
|||
|
|
<!-- -->
|
|||
|
|
|
|||
|
|
``` sql
|
|||
|
|
SELECT * FROM system.settings WHERE changed AND name='load_balancing'
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**See also**
|
|||
|
|
|
|||
|
|
- [Settings](../../operations/settings/index.md#session-settings-intro)
|
|||
|
|
- [Permissions for Queries](../../operations/settings/permissions-for-queries.md#settings_readonly)
|
|||
|
|
- [Constraints on Settings](../../operations/settings/constraints-on-settings.md)
|