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> System table containing information about existing data skipping indices in all the tables.

# system.data_skipping_indices

<h2 id="description">
  Description
</h2>

Contains information about existing data skipping indices in all the tables.

<h2 id="columns">
  Columns
</h2>

* `database` ([String](/reference/data-types/index)) — Database name.
* `table` ([String](/reference/data-types/index)) — Table name.
* `name` ([String](/reference/data-types/index)) — Index name.
* `type` ([String](/reference/data-types/index)) — Index type.
* `type_full` ([String](/reference/data-types/index)) — Index type expression from create statement.
* `expr` ([String](/reference/data-types/index)) — Expression for the index calculation.
* `creation` ([Enum8('Explicit' = 0, 'Implicit' = 1)](/reference/data-types/index)) — Whether the index was created implicitly (via add\_minmax\_index\_for\_numeric\_columns or similar)
* `granularity` ([UInt64](/reference/data-types/index)) — The number of granules in the block.
* `data_compressed_bytes` ([UInt64](/reference/data-types/index)) — The size of compressed data, in bytes.
* `data_uncompressed_bytes` ([UInt64](/reference/data-types/index)) — The size of decompressed data, in bytes.
* `marks_bytes` ([UInt64](/reference/data-types/index)) — The size of marks, in bytes.

<h2 id="example">
  Example
</h2>

```sql theme={null}
SELECT * FROM system.data_skipping_indices LIMIT 2 FORMAT Vertical;
```

```text theme={null}
Row 1:
──────
database:                default
table:                   user_actions
name:                    clicks_idx
type:                    minmax
type_full:               minmax
expr:                    clicks
creation:                Explicit
granularity:             1
data_compressed_bytes:   58
data_uncompressed_bytes: 6
marks_bytes:             48

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