system.settings

包含当前用户会话参数设置信息。

列：

name (String) — 设置名称。
value (String) — 设置值。
changed (UInt8) — 指示该设置是否在配置中被显式定义或被显式更改。
description (String) — 设置的简要说明。
min (Nullable(String)) — 通过约束为该设置指定的最小值（如果有）。如果设置没有最小值，则为 NULL。
max (Nullable(String)) — 通过约束为该设置指定的最大值（如果有）。如果设置没有最大值，则为 NULL。
disallowed_values (Array(String)) — 不允许的取值列表。
readonly (UInt8) — 指示当前用户是否可以更改该设置：
- 0 — 当前用户可以更改该设置。
- 1 — 当前用户不能更改该设置。
default (String) — 设置的默认值。
alias_for (String) — 如果该设置是其他设置的别名，则为原始设置的名称。
is_obsolete (UInt8) - 指示该设置是否已废弃。
tier (Enum8) — 此功能的支持级别。ClickHouse 的功能按层次组织，这些层次会根据当前的开发状态以及用户在使用它们时可以预期的行为而变化。取值：
- 'Production' — 功能稳定、安全可用，并且与其他生产级功能交互时不存在问题。
- 'Beta' — 功能稳定且安全。但与其他功能一起使用时的结果未知，不保证正确性。欢迎测试和反馈。
- 'Experimental' — 功能仍在开发中。仅面向开发人员和 ClickHouse 爱好者。该功能可能有效也可能无效，并且可能在任何时候被移除。
- 'Obsolete' — 不再受支持。要么已经被移除，要么将在未来版本中移除。

示例

下面的示例展示如何获取名称包含 min_i 的设置的信息。

SELECT *
FROM system.settings
WHERE name LIKE '%min_insert_block_size_%'
FORMAT Vertical

Row 1:
──────
name:        min_insert_block_size_rows
value:       1048449
changed:     0
description: Sets the minimum number of rows in the block that can be inserted into a table by an `INSERT` query. Smaller-sized blocks are squashed into bigger ones.

Possible values:

- Positive integer.
- 0 — Squashing disabled.
min:         ᴺᵁᴸᴸ
max:         ᴺᵁᴸᴸ
readonly:    0
type:        UInt64
default:     1048449
alias_for:   
is_obsolete: 0
tier:        Production

Row 2:
──────
name:        min_insert_block_size_bytes
value:       268402944
changed:     0
description: Sets the minimum number of bytes in the block which can be inserted into a table by an `INSERT` query. Smaller-sized blocks are squashed into bigger ones.

Possible values:

- Positive integer.
- 0 — Squashing disabled.
min:         ᴺᵁᴸᴸ
max:         ᴺᵁᴸᴸ
readonly:    0
type:        UInt64
default:     268402944
alias_for:   
is_obsolete: 0
tier:        Production

Row 3:
──────
name:        min_insert_block_size_rows_for_materialized_views
value:       0
changed:     0
description: Sets the minimum number of rows in the block which can be inserted into a table by an `INSERT` query. Smaller-sized blocks are squashed into bigger ones. This setting is applied only for blocks inserted into [materialized view](../../sql-reference/statements/create/view.md). By adjusting this setting, you control blocks squashing while pushing to materialized view and avoid excessive memory usage.

Possible values:

- Any positive integer.
- 0 — Squashing disabled.

**See Also**

- [min_insert_block_size_rows](/operations/settings/settings#min_insert_block_size_rows)
min:         ᴺᵁᴸᴸ
max:         ᴺᵁᴸᴸ
readonly:    0
type:        UInt64
default:     0
alias_for:   
is_obsolete: 0
tier:        Production

Row 4:
──────
name:        min_insert_block_size_bytes_for_materialized_views
value:       0
changed:     0
description: Sets the minimum number of bytes in the block which can be inserted into a table by an `INSERT` query. Smaller-sized blocks are squashed into bigger ones. This setting is applied only for blocks inserted into [materialized view](../../sql-reference/statements/create/view.md). By adjusting this setting, you control blocks squashing while pushing to materialized view and avoid excessive memory usage.

Possible values:

- Any positive integer.
- 0 — Squashing disabled.

**See also**

- [min_insert_block_size_bytes](/operations/settings/settings#min_insert_block_size_bytes)
min:         ᴺᵁᴸᴸ
max:         ᴺᵁᴸᴸ
readonly:    0
type:        UInt64
default:     0
alias_for:   
is_obsolete: 0
tier:        Production

使用 WHERE changed 在以下场景中很有用,例如需要检查:

配置文件中的设置是否已正确加载并生效。
当前会话中已变更的设置。

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

另请参阅