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

system.settings

Contains information about session settings for current user.

Columns:

• name (String) — Setting name.
• value (String) — Setting value.
• changed (UInt8) — Shows whether a setting is changed from its default value.
• description (String) — Short setting description.
• min (Nullable(String)) — Minimum value of the setting, if any is set via constraints. If the setting has no minimum value, contains NULL.
• max (Nullable(String)) — Maximum value of the setting, if any is set via constraints. If the setting has no maximum value, contains 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.

Example

The following example shows how to get information about settings which name contains 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 │
└─────────────────────────────────────────────┴───────────┴─────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴──────┴──────┴──────────┘

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.

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

See also

• Settings
• Permissions for Queries
• Constraints on Settings

Original article