mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-25 09:02:00 +00:00
51 lines
1.7 KiB
Markdown
51 lines
1.7 KiB
Markdown
---
|
|
slug: /zh/operations/system-tables/data_skipping_indices
|
|
---
|
|
# system.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](../../sql-reference/data-types/string.md)) — 数据库名称.
|
|
- `table` ([String](../../sql-reference/data-types/string.md)) — 数据表名称.
|
|
- `name` ([String](../../sql-reference/data-types/string.md)) — 索引名称.
|
|
- `type` ([String](../../sql-reference/data-types/string.md)) — 索引类型.
|
|
- `expr` ([String](../../sql-reference/data-types/string.md)) — 索引计算表达式.
|
|
- `granularity` ([UInt64](../../sql-reference/data-types/int-uint.md)) — 块中颗粒的数量.
|
|
- `data_compressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — 压缩数据的大小, 以字节为单位.
|
|
- `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.
|
|
- `marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — 标记的大小, 以字节为单位.
|
|
|
|
**示例**
|
|
|
|
```sql
|
|
SELECT * FROM system.data_skipping_indices LIMIT 2 FORMAT Vertical;
|
|
```
|
|
|
|
```text
|
|
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
|
|
```
|