> ## Documentation Index
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> Documentation for Apply patches from lightweight updates
# Apply patches from lightweight updates
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```sql theme={null}
ALTER TABLE [db.]table [ON CLUSTER cluster] APPLY PATCHES [IN PARTITION partition_id]
```
The command manually triggers the physical materialization of patch parts created by [lightweight `UPDATE`](/core/reference/statements/update) statements. It forcefully applies pending patches to the data parts by rewriting only the affected columns.
* It only works for tables in the [`MergeTree`](/core/reference/engines/table-engines/mergetree-family/mergetree) family (including [replicated](/core/reference/engines/table-engines/mergetree-family/replication) tables).
* This is a mutation operation and executes asynchronously in the background.
When to use APPLY PATCHES
Generally, you should not need to use `APPLY PATCHES`
Patch parts are normally applied automatically during merges when the [`apply_patches_on_merge`](/core/reference/settings/merge-tree-settings#apply_patches_on_merge) setting is enabled (default). However, you may want to manually trigger patch application in these scenarios:
* To reduce the overhead of applying patches during `SELECT` queries
* To consolidate multiple patch parts before they accumulate
* To prepare data for backup or export with patches already materialized
* When `apply_patches_on_merge` is disabled and you want to control when patches are applied
Examples
Apply all pending patches for a table:
```sql theme={null}
ALTER TABLE my_table APPLY PATCHES;
```
Apply patches only for a specific partition:
```sql theme={null}
ALTER TABLE my_table APPLY PATCHES IN PARTITION '2024-01';
```
Combine with other operations:
```sql theme={null}
ALTER TABLE my_table APPLY PATCHES, UPDATE column = value WHERE condition;
```
Monitoring patch application
You can monitor the progress of patch application using the [`system.mutations`](/core/reference/system-tables/mutations) table:
```sql theme={null}
SELECT * FROM system.mutations
WHERE table = 'my_table' AND command LIKE '%APPLY PATCHES%';
```
See also
* [Lightweight `UPDATE`](/core/reference/statements/update) - Create patch parts with lightweight updates
* [`apply_patches_on_merge` setting](/core/reference/settings/merge-tree-settings#apply_patches_on_merge) - Control automatic patch application during merges