5.Elasticsearch动态映射的使用

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发布于 2023-08-18 12:56:54

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发布于 2023-08-18 12:56:54

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ES可以自动检测新字段并根据数据自动添加到映射中。这是动态映射的一个强大特性，可以简化索引管理。但是，动态映射可能导致字段类型不一致和性能问题。因此，在生产环境中，最好在索引创建之前明确定义映射。

动态映射规则

null：不添加任何字段
true/false: boolean
浮点数：float
整数：long
对象：对象类型字段
数组：取决于第一个元素的类型
字符串：date\float\long\text-keyword

自动映射

直接塞入数据，默认自动创建索引

PUT lglbc_dynamic_mapping/_doc/1
{
  "string_field":"字符串",
  "date_field":"2023/07/29 10:00:00",
  "date_field2":"2023-07-29 10:00:00",
  "bool_field":true,
  "long_field":5,
  "object_field":{
    "name":"乐哥聊编程"
  },
  "float_field":4.5,
  "null_field":null
}

获取生成的映射

GET lglbc_dynamic_mapping/_mapping

可以看出，所有字段类型都是按照规则生成的,日期也能解析出来，但是注意到date_field2并没有被解析成日期类型，这是因为es默认不支持这种日期格式，所以自己配置

{
  "lglbc_dynamic_mapping": {
    "mappings": {
      "properties": {
        "bool_field": {
          "type": "boolean"
        },
        "date_field": {
          "type": "date",
          "format": "yyyy/MM/dd HH:mm:ss||yyyy/MM/dd||epoch_millis"
        },
        "date_field2": {
          "type": "text",
          "fields": {
            "keyword": {
              "type": "keyword",
              "ignore_above": 256
            }
          }
        },
        "float_field": {
          "type": "float"
        },
        "long_field": {
          "type": "long"
        },
        "object_field": {
          "properties": {
            "name": {
              "type": "text",
              "fields": {
                "keyword": {
                  "type": "keyword",
                  "ignore_above": 256
                }
              }
            }
          }
        },
        "string_field": {
          "type": "text",
          "fields": {
            "keyword": {
              "type": "keyword",
              "ignore_above": 256
            }
          }
        }
      }
    }
  }
}

手动配置，支持指定日期格式

PUT lglbc_dynamic_mapping
{
  "mappings": {
    "dynamic_date_formats": ["yyyy-MM-dd HH:mm:ss","yyyy/MM/dd HH:mm:ss"]
  }
}

GET lglbc_dynamic_mapping/_mapping

{
  "lglbc_dynamic_mapping": {
    "mappings": {
      "dynamic_date_formats": [
        "yyyy-MM-dd HH:mm:ss",
        "yyyy/MM/dd HH:mm:ss"
      ],
      "properties": {
        "bool_field": {
          "type": "boolean"
        },
        "date_field": {
          "type": "date",
          "format": "yyyy/MM/dd HH:mm:ss"
        },
        "date_field2": {
          "type": "date",
          "format": "yyyy-MM-dd HH:mm:ss"
        },
        "float_field": {
          "type": "float"
        },
        "long_field": {
          "type": "long"
        },
        "object_field": {
          "properties": {
            "name": {
              "type": "text",
              "fields": {
                "keyword": {
                  "type": "keyword",
                  "ignore_above": 256
                }
              }
            }
          }
        },
        "string_field": {
          "type": "text",
          "fields": {
            "keyword": {
              "type": "keyword",
              "ignore_above": 256
            }
          }
        }
      }
    }
  }
}

字符串数值自动转换

执行如下操作，string_int字段会被识别成text字段

PUT lglbc_dynamic_mapping/_doc/1
{
  "string_field":"字符串",
  "string_int":"10",
  "date_field":"2023/07/29 10:00:00",
  "date_field2":"2023-07-29 10:00:00",
  "bool_field":true,
  "long_field":5,
  "object_field":{
    "name":"乐哥聊编程"
  },
  "float_field":4.5,
  "null_field":null
}

配置mapping。使其能自动转换

PUT lglbc_dynamic_mapping
{
  "mappings": {
    "dynamic_date_formats": ["yyyy-MM-dd HH:mm:ss","yyyy/MM/dd HH:mm:ss"],
    "numeric_detection": true
  }
}

名称匹配指定类型

以long_开头且不以text结尾的字符串字段，将被映射成long类型

PUT lglbc_dynamic_mapping
{
  "mappings": {
    "dynamic_templates":[
      {
        "long_as_string":{
          "match_mapping_type":"string",
          "match":"long_*",
          "unmatch":"*_text",
          "mapping":{
            "type":"long"
          }
        }
      }]
  }
}

{
  "lglbc_dynamic_mapping": {
    "mappings": {
      "dynamic_templates": [
        {
          "long_as_string": {
            "match": "long_*",
            "unmatch": "*_text",
            "match_mapping_type": "string",
            "mapping": {
              "type": "long"
            }
          }
        }
      ],
      "properties": {
        "long_num": {
          "type": "long"
        },
        "long_text": {
          "type": "text",
          "fields": {
            "keyword": {
              "type": "keyword",
              "ignore_above": 256
            }
          }
        }
      }
    }
  }
}

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原始发表：2023-08-15，如有侵权请联系 cloudcommunity@tencent.com 删除

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