ClickHouse/docs/zh/operations/system-tables/data_skipping_indices.md

slug
/zh/operations/system-tables/data_skipping_indices

system.data_skipping_indices

包含有关所有表中现有数据跳过索引的信息.

列信息:

• database (String) — 数据库名称.
• table (String) — 数据表名称.
• name (String) — 索引名称.
• type (String) — 索引类型.
• expr (String) — 索引计算表达式.
• granularity (UInt64) — 块中颗粒的数量.
• data_compressed_bytes (UInt64) — 压缩数据的大小, 以字节为单位.
• data_uncompressed_bytes (UInt64) — 解压缩数据的大小, 以字节为单位.
• marks_bytes (UInt64) — 标记的大小, 以字节为单位.

示例

SELECT * FROM system.data_skipping_indices LIMIT 2 FORMAT Vertical;

Row 1:
──────
database:    default
table:       user_actions
name:        clicks_idx
type:        minmax
expr:        clicks
granularity: 1
data_compressed_bytes:   58
data_uncompressed_bytes: 6
marks:                   48

Row 2:
──────
database:    default
table:       users
name:        contacts_null_idx
type:        minmax
expr:        assumeNotNull(contacts_null)
granularity: 1
data_compressed_bytes:   58
data_uncompressed_bytes: 6
marks:                   48