ElasticSearch关于映射mapping介绍

墨蓝 2023-07-14 10:36 12阅读 0赞

\#首先我们还是先增加几个文档

PUT /myindex/article/1
    {
     "post_date": "2020-03-14",
     "title": "Java",
     "content": "java is the best language",
      "author_id": 119
    }
    
    PUT /myindex/article/2
    {"post_date": "2020-03-14" ,
      "title": "html",
      "content": "I like html",
      "author_id": 120
    }
    PUT /myindex/article/3
    {"post_date": "2020-03-14" ,
      "title": "es",
      "content": "Es is distributed document store" ,
      "author_id": 110
    }

#查看es的文档映射mapping的数据结构
    GET /myindex/article/_mapping

mapping数据结构如下：

{
      "myindex" : {
        "mappings" : {
          "article" : {
            "properties" : {
              "author_ id" : {
                "type" : "long"
              },
              "content" : {
                "type" : "text",
                "fields" : {
                  "keyword" : {
                    "type" : "keyword",
                    "ignore_above" : 256
                  }
                }
              },
              "post_ _date" : {
                "type" : "date"
              },
              "post_ date" : {
                "type" : "text",
                "fields" : {
                  "keyword" : {
                    "type" : "keyword",
                    "ignore_above" : 256
                  }
                }
              },
              "title" : {
                "type" : "text",
                "fields" : {
                  "keyword" : {
                    "type" : "keyword",
                    "ignore_above" : 256
                  }
                }
              }
            }
          }
        }
      }
    }

这里我们并没有为索引文档的数据结构做定义，但是我们发现es自动创建了 index type 以及type对应的mapping(dynamic mapping) 说明ElasticSearch能根据我们给的数据自动检测并且给定字段的数据类型

如果给定的  true  、false------>boolean

如果给定的字符串 "字符串"------>string（注意我这里用的是6.8.6版本 string已经被text或者keyword代替）

如果给定的数字   1、2------>long

如果给定的小数  12.34------>double

如果给定的时间   2020-03-14------->date

**什么是映射mapping？**

mapping定义了type中的每个字段的数据类型以及这些字段的如何分词的等相关属性

我们现在带查询一下添加的文档内容 GET /myindex/article/\_search

{
      "took" : 29,
      "timed_out" : false,
      "_shards" : {
        "total" : 5,
        "successful" : 5,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : 3,
        "max_score" : 1.0,
        "hits" : [
          {
            "_index" : "myindex",
            "_type" : "article",
            "_id" : "2",
            "_score" : 1.0,
            "_source" : {
              "post_ date" : "2020-03-14",
              "title" : "html",
              "content" : "I like html",
              "author_ id" : 120
            }
          },
          {
            "_index" : "myindex",
            "_type" : "article",
            "_id" : "1",
            "_score" : 1.0,
            "_source" : {
              "post_ date" : "2020-03-14",
              "title" : "Java",
              "content" : "java is the best language",
              "author_ id" : 119
            }
          },
          {
            "_index" : "myindex",
            "_type" : "article",
            "_id" : "3",
            "_score" : 1.0,
            "_source" : {
              "post_ _date" : "2020-03-14",
              "title" : "es",
              "content" : "Es is distributed document store",
              "author_ id" : 110
            }
          }
        ]
      }
    }

### **带条件的查询**  ###

\#查不出来  
GET /myindex/article/\_search?q=post\_date:2020

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3l3bDQ3MDgxMjA4Nw_size_16_color_FFFFFF_t_70][]

\#可以查出来  
GET /myindex/article/\_search?q=post\_date:2020-03-14

{
      "took" : 4,
      "timed_out" : false,
      "_shards" : {
        "total" : 5,
        "successful" : 5,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : 3,
        "max_score" : 1.0,
        "hits" : [
          {
            "_index" : "myindex",
            "_type" : "article",
            "_id" : "2",
            "_score" : 1.0,
            "_source" : {
              "post_date" : "2020-03-14",
              "title" : "html",
              "content" : "I like html",
              "author_id" : 120
            }
          },
          {
            "_index" : "myindex",
            "_type" : "article",
            "_id" : "1",
            "_score" : 1.0,
            "_source" : {
              "post_date" : "2020-03-14",
              "title" : "Java",
              "content" : "java is the best language",
              "author_id" : 119
            }
          },
          {
            "_index" : "myindex",
            "_type" : "article",
            "_id" : "3",
            "_score" : 1.0,
            "_source" : {
              "post_date" : "2020-03-14",
              "title" : "es",
              "content" : "Es is distributed document store",
              "author_id" : 110
            }
          }
        ]
      }
    }

\#可以查出来  
GET /myindex/article/\_search?q=content:html![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3l3bDQ3MDgxMjA4Nw_size_16_color_FFFFFF_t_70 1][]

## **注意？** ##

**这是因为ElasticSearch映射mapping进行指定的，post\_date是日期类型，而content是字符串类型所以字符串就查询出来了。****像日期date类型和数字long类型要进行精确查询才可以查询，而说明日期和数字类型没有进行分词，而字符串进行了分词。字符串text类型默认进行了分词的**

**到这里我们知道了mapping有两个作用，一是规定自定的类型，二是规定相关字段的属性（比如是不是进行分词）**

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3l3bDQ3MDgxMjA4Nw_size_16_color_FFFFFF_t_70 1]: /images/20230529/054959b923bf4b53b06ea8fd727ef9af.png