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Merge branch 'master' into persistent_nukeeper_log_storage
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@ -25,6 +25,7 @@ The following actions are supported:
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- [COMMENT COLUMN](#alter_comment-column) — Adds a text comment to the column.
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- [MODIFY COLUMN](#alter_modify-column) — Changes column’s type, default expression and TTL.
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- [MODIFY COLUMN REMOVE](#modify-remove) — Removes one of the column properties.
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- [RENAME COLUMN](#alter_rename-column) — Renames an existing column.
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These actions are described in detail below.
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@ -183,6 +184,22 @@ ALTER TABLE table_with_ttl MODIFY COLUMN column_ttl REMOVE TTL;
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- [REMOVE TTL](ttl.md).
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## RENAME COLUMN {#alter_rename-column}
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Renames an existing column.
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Syntax:
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```sql
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ALTER TABLE table_name RENAME COLUMN column_name TO new_column_name;
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```
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**Example**
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```sql
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ALTER TABLE table_with_ttl RENAME COLUMN column_ttl TO column_ttl_new;
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```
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## Limitations {#alter-query-limitations}
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The `ALTER` query lets you create and delete separate elements (columns) in nested data structures, but not whole nested data structures. To add a nested data structure, you can add columns with a name like `name.nested_name` and the type `Array(T)`. A nested data structure is equivalent to multiple array columns with a name that has the same prefix before the dot.
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