如果不允许修改索引字段类型，只能重建索引

步骤

1. 新建一个索引
2. 数据迁移
3. 删除旧索引
4. 别名引用

1、准备工作

1.1、查看版本号

GET /

响应

{"name": "jxZZibZ","cluster_name": "elasticsearch","cluster_uuid": "23IcxgHqTniM4wOGyl03Pw","version": {"number": "5.6.16","build_hash": "3a740d1","build_date": "2019-03-13T15:33:36.565Z","build_snapshot": false,"lucene_version": "6.6.1"},"tagline": "You Know, for Search"
}

可以看到，我所使用的ES 版本号为：5.6.16

1.2、创建旧索引

旧索引名为old-index，包含2个字段：id、username

PUT /old-index
{"mappings": {"doc": {"properties": {"id": {"type": "integer"},"username": {"type": "text"}}}}
}

响应

{"acknowledged": true,"shards_acknowledged": true,"index": "old-index"
}

1.3、添加两条数据

POST /old-index/doc
{"id": 1000,"username": "root"
}POST /old-index/doc
{"id": 1001,"username": "other"
}

1.4、查看数据

GET /old-index/_search

响应

{"took": 0,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 2,"max_score": 1,"hits": [{"_index": "old-index","_type": "doc","_id": "AY1pDh-BNp3AgKn6mtEj","_score": 1,"_source": {"id": 1000,"username": "root"}},{"_index": "old-index","_type": "doc","_id": "AY1pDikjNp3AgKn6mtEk","_score": 1,"_source": {"id": 1001,"username": "other"}}]}
}

2、新建一个索引

2.1、查看旧索引的mapping

GET /old-index/_mapping

响应

{"old-index": {"mappings": {"doc": {"properties": {"id": {"type": "integer"},"username": {"type": "text"}}}}}
}

2.2、新建索引

新的索引名为new-reindex，将id 字段的类型从integer 改为keyword

PUT /new-reindex
{"mappings": {"doc": {"properties": {"id": {"type": "keyword"},"username": {"type": "text"}}}}
}

3、数据迁移

3.1、使用异步任务迁移数据

POST /_reindex?wait_for_completion=false
{"source": {"index": "old-index","size": 10000},"dest": {"index": "new-index"}
}

响应

{"task": "jxZZibZPQ_mViMJHQyFz5w:7335"
}

如果数据量较大，容易出现 Gateway Time-out ，所以我添加了参数wait_for_completion=false，让其后台执行

{"statusCode": 504,"error": "Gateway Time-out","message": "Client request timeout"
}

3.2、查看任务状态

GET /_tasks/jxZZibZPQ_mViMJHQyFz5w:7335

{"completed": true,"task": {"node": "jxZZibZPQ_mViMJHQyFz5w","id": 7335,"type": "transport","action": "indices:data/write/reindex","status": {"total": 2,"updated": 0,"created": 2,"deleted": 0,"batches": 1,"version_conflicts": 0,"noops": 0,"retries": {"bulk": 0,"search": 0},"throttled_millis": 0,"requests_per_second": -1,"throttled_until_millis": 0},"description": "reindex from [old-index] to [new-index]","start_time_in_millis": 1706864890889,"running_time_in_nanos": 105811530,"cancellable": true},"response": {"took": 105,"timed_out": false,"total": 2,"updated": 0,"created": 2,"deleted": 0,"batches": 1,"version_conflicts": 0,"noops": 0,"retries": {"bulk": 0,"search": 0},"throttled_millis": 0,"requests_per_second": -1,"throttled_until_millis": 0,"failures": []}
}

4、删除旧索引

4.1、确认索引数据

查看新旧索引中的数据总量是否相等

GET /old-index/_countGET /new-index/_count

响应

{"count": 2,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0}
}

4.2、删除旧索引

确认数据已迁移完成，可以删除旧的索引了

DELETE /old-index

响应

{"acknowledged": true
}

5、别名引用

5.1、创建别名

PUT /new-index/_alias/old-index

响应

{"acknowledged": true
}

5.2、查看别名

GET _cat/aliases

old-index    new-index     - - -

5.3、使用别名

新旧索引都可以使用了

GET /old-index/_searchGET /new-index/_search

参考文章

• 如何在Elasticsearch中改变字段类型？