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48 lines
1.6 KiB
Markdown
48 lines
1.6 KiB
Markdown
# system.data_skipping_indices {#system-data-skipping-indices}
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Contains information about existing data skipping indices in all the tables.
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Columns:
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- `database` ([String](../../sql-reference/data-types/string.md)) — Database name.
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- `table` ([String](../../sql-reference/data-types/string.md)) — Table name.
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- `name` ([String](../../sql-reference/data-types/string.md)) — Index name.
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- `type` ([String](../../sql-reference/data-types/string.md)) — Index type.
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- `expr` ([String](../../sql-reference/data-types/string.md)) — Expression for the index calculation.
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- `granularity` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The number of granules in the block.
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- `data_compressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The size of compressed data, in bytes.
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- `data_uncompressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The size of decompressed data, in bytes.
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- `marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The size of marks, in bytes.
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**Example**
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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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