> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-mintlify-8c05c8a2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Documentation for Manipulating Column Statistics

# Manipulating Column Statistics

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            Not supported in ClickHouse Cloud
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The following operations are available:

* `ALTER TABLE [db].table ADD STATISTICS [IF NOT EXISTS] (column list) TYPE (type list)` - Adds statistic description to tables metadata.

* `ALTER TABLE [db].table MODIFY STATISTICS (column list) TYPE (type list)` - Modifies statistic description to tables metadata.

* `ALTER TABLE [db].table DROP STATISTICS [IF EXISTS] (column list)` - Removes statistics from the metadata of the specified columns and deletes all statistics objects in all parts for the specified columns.

* `ALTER TABLE [db].table CLEAR STATISTICS [IF EXISTS] (column list)` - Deletes all statistics objects in all parts for the specified columns. Statistics objects can be rebuild using `ALTER TABLE MATERIALIZE STATISTICS`.

* `ALTER TABLE [db.]table MATERIALIZE STATISTICS (ALL | [IF EXISTS] (column list))` - Rebuilds the statistic for columns. Implemented as a [mutation](/reference/statements/alter/index#mutations).

The first two commands are lightweight in a sense that they only change metadata or remove files.

Also, they are replicated, syncing statistics metadata via ZooKeeper.

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

Adding two statistics types to two columns:

```sql theme={null}
ALTER TABLE t1 MODIFY STATISTICS c, d TYPE TDigest, Uniq;
```

<Note>
  Statistic are supported only for [`*MergeTree`](/reference/engines/table-engines/mergetree-family/mergetree) engine tables (including [replicated](/reference/engines/table-engines/mergetree-family/replication) variants).
</Note>