由于ElasticSearch没有像数据库一样可以直接字段数据类型的方法，因此需要通过创建中间索引:data_index_1，备份数据到中间索引:data_index_1，然后删除原索引: data_index，重新创建正确数据类型索引：data_index，再把中间索引:data_index_1的数据备份到新创建索引：data_index。语句通过kibana的 dev_tools/console 执行。

索引mapping，可通过到Kibana查看索引的mapping，这是我们需要修改的字段rcvtime的类型

操作系统：CentOS7.4

ES版本：elasticsearch-7.16.3

kibana版本：kibana-7.16.3

操作步骤：

1.创建一个中间索引
2.向中间索引备份源索引的数据(mapping)
3.查询确认数据是否copy过去
4.删除有问题的索引
5.重新创建同名的索引(★字段类型修改正确★)
6.从中间索引还原到源索引的数据
7.删除中间索引

 参考脚本，在kibana执行：

# 1. 创建一个中间索引

# 创建索引和设置正确的字段Mapping
PUT mail_center.received_1
{
	"settings": {
	      "index": {
	        "max_result_window" : 100000000
	      },
        "number_of_shards": 3,
        "number_of_replicas": 0
    },
	"mappings": {
      "properties": {
        "rcvtime": {
          "type":   "date",
          "format": "yyyy-MM-dd HH:mm:ss"
        },
	      "fetchtime": {
          "type":   "date",
          "format": "yyyy-MM-dd HH:mm:ss"
        },
      	"gmcrcvtime": {
          "type":   "date",
          "format": "yyyy-MM-dd HH:mm:ss"
        }
      }
    }
}



# 2. 向中间索引备份源索引的数据

# 重建索引
POST _reindex
{
  "source": {
    "index": "mail_center.received"
  },
  "dest": {
    "index": "mail_center.received_1"
  }
}


# 3.查询确认数据是否copy过去

GET /mail_center.received/_doc/_search

GET /mail_center.received_1/_doc/_search

# 强制执行一次refresh
POST /mail_center.received_1/_refresh

# 4.删除源索引

# 删除源索引
DELETE mail_center.received


# 5.重新创建同名的索引(★字段类型修改正确★)

#创建索引和Mapping
PUT mail_center.received
{
	"settings": {
	      "index": {
	        "max_result_window" : 100000000
	      },
        "number_of_shards": 3,
        "number_of_replicas": 0
    },
	"mappings": {
      "properties": {
        "rcvtime": {
          "type":   "date",
          "format": "yyyy-MM-dd HH:mm:ss"
        },
	      "fetchtime": {
          "type":   "date",
          "format": "yyyy-MM-dd HH:mm:ss"
        },
      	"gmcrcvtime": {
          "type":   "date",
          "format": "yyyy-MM-dd HH:mm:ss"
        }
      }
    }
}


# 6. 从中间索引还原到源索引的数据
# 重建索引
POST _reindex
{
  "source": {
    "index": "mail_center.received_1"
  },
  "dest": {
    "index": "mail_center.received"
  }
}


# 7. 删除中间索引
DELETE mail_center.received_1

索引文档及数量可以通过kibana的index management查看

http://local.elasticsearch:5601/app/management/data/index_management/indices

如果显示不准确可以在kibana执行强制刷新 

POST /mail_center.received_1/_refresh

下图是修改后的字段mapping