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48 lines
1.6 KiB
Markdown
48 lines
1.6 KiB
Markdown
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# system.data_skipping_indices {#system-data-skipping-indices}
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包含有关所有表中现有数据跳过索引的信息.
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列信息:
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- `database` ([String](../../sql-reference/data-types/string.md)) — 数据库名称.
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- `table` ([String](../../sql-reference/data-types/string.md)) — 数据表名称.
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- `name` ([String](../../sql-reference/data-types/string.md)) — 索引名称.
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- `type` ([String](../../sql-reference/data-types/string.md)) — 索引类型.
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- `expr` ([String](../../sql-reference/data-types/string.md)) — 索引计算表达式.
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- `granularity` ([UInt64](../../sql-reference/data-types/int-uint.md)) — 块中颗粒的数量.
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- `data_compressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — 压缩数据的大小, 以字节为单位.
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- `data_uncompressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — 解压缩数据的大小, 以字节为单位.
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- `marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — 标记的大小, 以字节为单位.
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**示例**
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```sql
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SELECT * FROM system.data_skipping_indices LIMIT 2 FORMAT Vertical;
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```
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```text
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Row 1:
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──────
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database: default
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table: user_actions
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name: clicks_idx
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type: minmax
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expr: clicks
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granularity: 1
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data_compressed_bytes: 58
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data_uncompressed_bytes: 6
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marks: 48
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Row 2:
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──────
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database: default
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table: users
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name: contacts_null_idx
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type: minmax
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expr: assumeNotNull(contacts_null)
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granularity: 1
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data_compressed_bytes: 58
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data_uncompressed_bytes: 6
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marks: 48
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```
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