merge_tree_settings

包含有关 MergeTree 表设置的信息。

列

• name (字符串) — 设置名称。
• value (字符串) — 设置值。
• changed (UInt8) — 设置是否在配置中显式定义或显式更改。
• description (字符串) — 设置描述。
• min (可空(字符串)) — 设置的最小值（如果通过 约束 设置）。如果设置没有最小值，则包含 NULL。
• max (可空(字符串)) — 设置的最大值（如果通过 约束 设置）。如果设置没有最大值，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 — 当前用户无法更改设置。
• type (字符串) — 设置类型（实现特定的字符串值）。
• is_obsolete (UInt8) - 显示设置是否已过时。

示例

SELECT * FROM system.merge_tree_settings LIMIT 4 FORMAT Vertical;

Row 1:
──────
name:        min_compress_block_size
value:       0
changed:     0
description: When granule is written, compress the data in buffer if the size of pending uncompressed data is larger or equal than the specified threshold. If this setting is not set, the corresponding global setting is used.
min:         ____
max:         ____
readonly:    0
type:        UInt64
is_obsolete: 0

Row 2:
──────
name:        max_compress_block_size
value:       0
changed:     0
description: Compress the pending uncompressed data in buffer if its size is larger or equal than the specified threshold. Block of data will be compressed even if the current granule is not finished. If this setting is not set, the corresponding global setting is used.
min:         ____
max:         ____
readonly:    0
type:        UInt64
is_obsolete: 0

Row 3:
──────
name:        index_granularity
value:       8192
changed:     0
description: How many rows correspond to one primary key value.
min:         ____
max:         ____
readonly:    0
type:        UInt64
is_obsolete: 0

Row 4:
──────
name:        max_digestion_size_per_segment
value:       268435456
changed:     0
description: Max number of bytes to digest per segment to build GIN index.
min:         ____
max:         ____
readonly:    0
type:        UInt64
is_obsolete: 0

4 rows in set. Elapsed: 0.009 sec.