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23 lines
928 B
Markdown
23 lines
928 B
Markdown
---
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slug: /en/sql-reference/statements/alter/apply-deleted-mask
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sidebar_position: 46
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sidebar_label: APPLY DELETED MASK
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---
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# Apply mask of deleted rows
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``` sql
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ALTER TABLE [db].name [ON CLUSTER cluster] APPLY DELETED MASK [IN PARTITION partition_id]
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```
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The command applies mask created by [lightweight delete](/docs/en/sql-reference/statements/delete) and forcefully removes rows marked as deleted from disk. This command is a heavyweight mutation, and it semantically equals to query ```ALTER TABLE [db].name DELETE WHERE _row_exists = 0```.
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:::note
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It only works for tables in the [`MergeTree`](../../../engines/table-engines/mergetree-family/mergetree.md) family (including [replicated](../../../engines/table-engines/mergetree-family/replication.md) tables).
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:::
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**See also**
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- [Lightweight deletes](/docs/en/sql-reference/statements/delete)
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- [Heavyweight deletes](/docs/en/sql-reference/statements/alter/delete.md)
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