(56)ElasticSearch之dynamic mapping策略

  本篇分3部分说一下ElasticSearch的动态映射策略。

  1、dynamic陌生字段处理配置

  添加文档时,如果遇到了mapping里面没有定义的字段会怎样呢?这就依赖创建mapping时的dynamic配置情况,该属性参数有3种配置值:

  1)true:遇到陌生字段就自动映射,ElasticSearch的默认值

  2)false:遇到陌生字段就忽略

  3)strict:遇到陌生字段就报错

  下面进行演示说明:

PUT /lib
{
    "settings":{
        "number_of_shards":3,
        "number_of_replicas":0
      },
        "mappings":{
            "user":{
                "dynamic":"strict",
                "properties":{
                    "name":{"type":"text"},
                    "address":{
                      "type":"object",
                      "dynamic":true
                    }
                }
            }
        }
}

  类型user中定义了dynamic,其值为strict,也就是说如果添加的文档里出现了name和address以外的字段就会报错。address中又定义了dynamic,值为true,意思是说如果address里面出现了其它字段,es会对其自动映射(因为address是object类型,可以包含其它字段)。dynamic写的位置不动,管的范围不一样。

  添加示例,正常不报错

put /lib/user/1
{
    "name":"lisi",
    "address":{
      "province":"beijing",
      "city":"beijing"
    }
}

  添加结果

{
  "_index": "lib",
  "_type": "user",
  "_id": "1",
  "_version": 1,
  "result": "created",
  "_shards": {
    "total": 1,
    "successful": 1,
    "failed": 0
  },
  "_seq_no": 0,
  "_primary_term": 1
}

  添加示例,报错

put /lib/user/2
{
    "name":"lisi",
    "age":23,
    "address":{
      "province":"beijing",
      "city":"beijing"
    }
}

  添加结果:

{
  "error": {
    "root_cause": [
      {
        "type": "strict_dynamic_mapping_exception",
        "reason": "mapping set to strict, dynamic introduction of [age] within [user] is not allowed"
      }
    ],
    "type": "strict_dynamic_mapping_exception",
    "reason": "mapping set to strict, dynamic introduction of [age] within [user] is not allowed"
  },
  "status": 400
}

  2、date_detection默认日期格式的识别为date类型配置

  date_detection默认值是true,默认会按照一定格式识别date,比如yyyy-MM-dd会默认识别为日期类型

  如下面的1990-12-12没有指明字段类型,会根据格式默认为日期类型

hput /lib/user/1
{
    "name":"1990-12-12",
    "address":{
      "province":"beijing",
      "city":"beijing"
    }
}

  假如希望写成了日期的格式,也不会识别为date的类型,应该设置为false,如下:

PUT /lib
{
    "settings":{
        "number_of_shards":3,
        "number_of_replicas":0
      },
      "mappings":{
          "user":{
              "date_detection":false
          }
      }
}

  3、dymamic mapping template(type)  定制动态映射模板配置

  请看下面的例子,定义了索引my_index,类型my_type,在mapping中指明了类型和分词器,但是没有指明字段。但是定义了match和match_mapping_type,意思是:如果字段的名字以_en结尾就使用下面的模板;如果没有匹配就不使用该模板。配置_en的是默认的english分词器,没有匹配的是stardand标准分词器。

PUT /my_index
{
  "mappings": {
    "my_type":{
      "dynamic_templates":[
          {
            "en":{
              "match":"*_en",
              "match_mapping_type":"string",
              "mapping":{
                "type":"text",
                "analyzer":"english"
              }
            }
          }
        ]
    }
  }
}
PUT /my_index/my_type/1
{
  "title_en":"this is my dog"
}
PUT /my_index/my_type/2
{
  "title":"this is my cat"
}

  测试:id为1的文档匹配了模板,使用的是english分词器,该分词器忽略了 is a an等单词,根据 is 不会查询出文档,如下:

GET /my_index/my_type/_search
{
  "query":{
    "match": {
      "title_en": "is"
    }
  }
}

  查询结果:

{
  "took": 3,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 0,
    "max_score": null,
    "hits": []
  }
}

  测试:id为2的文档没有匹配该模板,使用的是标准分词器,该分词器没有忽略 is a an等单词,根据 is 可以查询出文档,如下:

GET /my_index/my_type/_search
{
  "query":{
    "match": {
      "title": "is"
    }
  }
}

  查询结果:

{
  "took": 4,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.2876821,
    "hits": [
      {
        "_index": "my_index",
        "_type": "my_type",
        "_id": "2",
        "_score": 0.2876821,
        "_source": {
          "title": "this is my cat"
        }
      }
    ]
  }
}

 

(56)ElasticSearch之dynamic mapping策略

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