ES中nest join

• 2020 年 1 月 21 日
• 笔记

nested 类型是一个特殊object数据类型，允许数组的object的字段可以被独立的查询出来。

数据类型是如何被封装的

在lucene中没有嵌套object的概念，所以ES的用一个简单的数据数据列表来表示一个复杂的层次数据实体，例如一个博客和评论的实体：

PUT  nesttest/_doc  {      "blog_title": "开篇-es的nest的使用",      "blog_content": "从本篇文章开始，我会分享给大家canvas绘制的各种基础图形和酷炫的图形",      "tags": [          "Java",          "es"      ],      "hit_count": 5,      "commet": [          {              "commet_user": "tom",              "commet_content": "good Job",              "commet_time": "2019-02-26",               "commet_location": "beijing"          },          {              "commet_user": "john",              "commet_content": "clearly,tks",              "commet_time": "2019-02-23"              ,               "commet_location": "shanghai"          },          {              "commet_user": "lily",              "commet_content": "it's too hard ",              "commet_time": "2019-02-22"             ,               "commet_location": "shenzhen"          }      ],      "create_time": "2019-02-26"  }

其中commet类型会被转化成一个数组的形式如下：

{    ...    "commet.commet_user":["tom","john","lily"],    ...     "commet.commet_location":["beijing","shanghai","shenzhen"],  }

而当执行查询的时候：

GET nesttest/_search  {    "query": {      "bool": {        "must": [          { "match": { "commet.commet_user": "john" }},          { "match": { "commet.commet_location":  "shenzhen" }}        ]      }    }  }

发现查询结果如下：

{  ...        "hits" : [        {          "_index" : "nest",          "_type" : "_doc",          "_id" : "pe0iKWkBulkJdQfMSgyV",          "_score" : 0.5753642,          "_source" : {            "blog_title" : "2019-01-05",            "blog_content" : "从本篇文章开始，我会分享给大家canvas绘制的各种基础图形和酷炫的图形",            "tags" : [              "Java",              "es"            ],            "hit_count" : 5,            "commet" : [              {                "commet_user" : "tom",                "commet_content" : "good Job",                "commet_time" : "2019-02-26",                "commet_location" : "beijing"              },              {                "commet_user" : "john",                "commet_content" : "clearly,tks",                "commet_time" : "2019-02-23",                "commet_location" : "shanghai"              },              {                "commet_user" : "lily",                "commet_content" : "it's too hard ",                "commet_time" : "2019-02-22",                "commet_location" : "shenzhen"              }            ],            "create_time" : "2019-02-26"          }        }      ]    }  }  

上面把所有的结果都列出来了， 但是 john的不在shenzhen啊？所以需要把commet定义为nested 类型。

定义nested类型

PUT nest_new/_mapping/_doc  {      "properties": {          "blog_title": {              "type": "text"          },          "blog_content": {              "type": "text"          },          "tags": {              "type": "keyword"          },          "hit_count": {              "type": "keyword"          },          "commet": {              "type": "nested",//这里              "properties": {                  "commet_user": {                      "type": "text"                  },                  "commet_content": {                      "type": "text"                  },                  "commet_time": {                      "type": "date"                  },                  "commet_location": {                      "type": "keyword"                  }              }          },          "create_time": {              "type": "date"          },          "datachange_lasttime": {              "format": "strict_date_optional_time||epoch_millis",              "type": "date"          }      }  }

ES嵌套深度被限制在50层