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

slug
/en/operations/system-tables/settings

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.
• default (String) — Setting default value.
• is_obsolete (UInt8) - Shows whether a setting is obsolete.

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─_─type─────────_─default───_─alias_for─_─is_obsolete─┐
│ min_insert_block_size_rows                         │ 1048449   │       0 │ Squash blocks passed to INSERT query to specified size in rows, if blocks are not big enough.                                                                         │ ____ │ ____ │        0 │ UInt64       │ 1048449   │           │           0 │
│ min_insert_block_size_bytes                        │ 268402944 │       0 │ Squash blocks passed to INSERT query to specified size in bytes, if blocks are not big enough.                                                                        │ ____ │ ____ │        0 │ UInt64       │ 268402944 │           │           0 │
│ min_insert_block_size_rows_for_materialized_views  │ 0         │       0 │ Like min_insert_block_size_rows, but applied only during pushing to MATERIALIZED VIEW (default: min_insert_block_size_rows)                                           │ ____ │ ____ │        0 │ UInt64       │ 0         │           │           0 │
│ min_insert_block_size_bytes_for_materialized_views │ 0         │       0 │ Like min_insert_block_size_bytes, but applied only during pushing to MATERIALIZED VIEW (default: min_insert_block_size_bytes)                                         │ ____ │ ____ │        0 │ UInt64       │ 0         │           │           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. │ ____ │ ____ │        0 │ Milliseconds │ 1000      │           │           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
• SHOW SETTINGS statement