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60 lines
1.4 KiB
Markdown
60 lines
1.4 KiB
Markdown
---
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slug: /zh/sql-reference/statements/alter/setting
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sidebar_position: 38
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sidebar_label: SETTING
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---
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# 表设置操作 {#table_settings_manipulations}
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这是一组更改表设置的操作。你可以修改设置或将其重置为默认值。单个查询可以同时更改多个设置。 如果指定名称的设置不存在，则查询会引发异常。
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**语法**
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``` sql
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ALTER TABLE [db].name [ON CLUSTER cluster] MODIFY|RESET SETTING ...
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```
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:::note
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这些查询只能应用于 [MergeTree](../../../engines/table-engines/mergetree-family/mergetree.md) 表。
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:::
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## 修改设置 {#alter_modify_setting}
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更改表设置
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**语法**
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```sql
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MODIFY SETTING setting_name=value [, ...]
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```
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**示例**
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```sql
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CREATE TABLE example_table (id UInt32, data String) ENGINE=MergeTree() ORDER BY id;
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ALTER TABLE example_table MODIFY SETTING max_part_loading_threads=8, max_parts_in_total=50000;
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```
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## 重置设置 {#alter_reset_setting}
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重置表设置为默认值。如果设置处于默认状态，则不采取任何操作。
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**语法**
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```sql
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RESET SETTING setting_name [, ...]
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```
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**示例**
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```sql
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CREATE TABLE example_table (id UInt32, data String) ENGINE=MergeTree() ORDER BY id
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SETTINGS max_part_loading_threads=8;
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ALTER TABLE example_table RESET SETTING max_part_loading_threads;
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```
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**参见**
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- [MergeTree settings](../../../operations/settings/merge-tree-settings.mdx)
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