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24 lines
1.1 KiB
Markdown
24 lines
1.1 KiB
Markdown
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---
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toc_hidden_folder: true
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toc_priority: 42
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toc_title: INDEX
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---
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# 操作数据跳过索引 {#manipulations-with-data-skipping-indices}
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可以使用以下操作：
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- `ALTER TABLE [db].name ADD INDEX name expression TYPE type GRANULARITY value [FIRST|AFTER name]` - 向表元数据添加索引描述。
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- `ALTER TABLE [db].name DROP INDEX name` - 从表元数据中删除索引描述并从磁盘中删除索引文件。
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- `ALTER TABLE [db.]table MATERIALIZE INDEX name IN PARTITION partition_name` - 查询在分区`partition_name`中重建二级索引`name`。 操作为[mutation](../../../../sql-reference/statements/alter/index.md#mutations).
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前两个命令是轻量级的，它们只更改元数据或删除文件。
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Also, they are replicated, syncing indices metadata via ZooKeeper.
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此外，它们会被复制，会通过ZooKeeper同步索引元数据。
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!!! note "注意"
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索引操作仅支持具有以下特征的表 [`*MergeTree`](../../../../engines/table-engines/mergetree-family/mergetree.md)引擎 (包括[replicated](../../../../engines/table-engines/mergetree-family/replication.md)).
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