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system.settings

包含当前用户会话设置的信息。

列：

  • name (String) — 设置名称。
  • value (String) — 设置值。
  • changed (UInt8) — 显示设置是否在配置中明确定义或显式更改。
  • description (String) — 短设置描述。
  • min (Nullable(String)) — 设置的最小值，如果通过 constraints 设置了最小值。如果该设置没有最小值，则包含 NULL。
  • max (Nullable(String)) — 设置的最大值，如果通过 constraints 设置了最大值。如果该设置没有最大值，则包含 NULL。
  • readonly (UInt8) — 显示当前用户是否可以更改设置：
    • 0 — 当前用户可以更改设置。
    • 1 — 当前用户不能更改设置。
  • default (String) — 设置的默认值。
  • is_obsolete (UInt8) - 显示一个设置是否过时。
  • tier (Enum8) — 该功能的支持级别。ClickHouse 功能分为不同的层级，依赖于其开发的当前状态和使用时的预期。值：
    • 'Production' — 该功能稳定、可安全使用并且与其他 production 功能没有交互问题。
    • 'Beta' — 该功能稳定且安全。与其他功能一起使用的结果未知，并且正确性不能得到保证。欢迎进行测试和报告。
    • 'Experimental' — 该功能正在开发中。仅供开发人员和ClickHouse爱好者使用。该功能可能有效也可能无效，并且可能在任何时候被删除。
    • 'Obsolete' — 不再支持。要么已经删除，要么将会在未来版本中删除。

示例

以下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 是有用的，例如，当你想检查：

  • 配置文件中的设置是否正确加载并正在使用。
  • 当前会话中已更改的设置。
SELECT * FROM system.settings WHERE changed AND name='load_balancing'

另见