本文在新建类型的时候报如下错误：

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_argument_exception",
        "reason": "Rejecting mapping update to [myes] as the final mapping would have more than 1 type: [user1, user]"
      }
    ],
    "type": "illegal_argument_exception",
    "reason": "Rejecting mapping update to [myes] as the final mapping would have more than 1 type: [user1, user]"
  },
  "status": 400
}

在springboot启动的时候也报对应的错误：

Caused by: java.lang.IllegalArgumentException: Rejecting mapping update to [myes] as the final mapping would have more than 1 type: [topic, user]

然后发现，elasticsearch 6.0.0及之后移除了一个索引允许映射多个类型的操作（Removal of mapping types）。也就是不能用索引跟数据库的database相对比，类型跟表对比了，这样会产生误解。具体原因以后会详细研究。先记录下来。