一、Index Template

1、概念

Index Templates帮助我们设定Mappings和Settings，并按照一定的规则自动匹配到新创建的索引上。

• 模板仅在一个索引被新创建时，才会产生作用。修改模板不会影响已创建的索引。
• 可以设定多个模板，这些设置会merge在一起。
• 可以指定order的数值，控制merge的过程。

2、工作方式

当一个索引创建的时候：

• 应用Elasticsearch默认的settings和mappings。
• 应用order数值低的Index Template的设定。
• 应用order数值高的Index Template的设定，之前的设定会被覆盖掉。
• 应用创建索引的时候，如果用户指定了Settings和Mappings，就会覆盖之前模板的设定。

3、案例实践

ES默认的settings和mappings

// 数字字符串被映射成text，日期字符串被映射成日期，因为是使用ES默认的settings和mappings
PUT ttemplate/_doc/1
{
	"someNumber":"1",
	"someDate":"2019/01/01"
}
GET ttemplate/_mapping
GET ttemplate/_settings

// mapping
{
  "ttemplate" : {
    "mappings" : {
      "properties" : {
        "someDate" : {
          "type" : "date",
          "format" : "yyyy/MM/dd HH:mm:ss||yyyy/MM/dd||epoch_millis"
        },
        "someNumber" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        }
      }
    }
  }
}

// settings
{
  "ttemplate" : {
    "settings" : {
      "index" : {
        "creation_date" : "1684892721593",
        "number_of_shards" : "1",
        "number_of_replicas" : "1",
        "uuid" : "rgNZ2YLCSO2hfr1mqU41qg",
        "version" : {
          "created" : "7010099"
        },
        "provided_name" : "ttemplate"
      }
    }
  }
}

创建两个Index Template

#Create a default template
PUT _template/template_default
{
  "index_patterns": ["*"],
  "order" : 0,
  "version": 1,
  "settings": {
    "number_of_shards": 1,
    "number_of_replicas":1
  }
}


PUT /_template/template_test
{
    "index_patterns" : ["test*"],
    "order" : 1,
    "settings" : {
    	"number_of_shards": 1,
        "number_of_replicas" : 2
    },
    "mappings" : {
      // 关闭日期类型推断
    	"date_detection": false,
      // 开启数字类型推断
    	"numeric_detection": true
    }
}

#查看template信息
GET /_template/template_default
GET /_template/temp*

插入index以test开头

#写入新的数据，index以test开头
PUT testtemplate/_doc/1
{
	"someNumber":"1",
	"someDate":"2019/01/01"
}
GET testtemplate/_mapping
GET testtemplate/_settings

// mapping
{
  "testtemplate" : {
    "mappings" : {
      "date_detection" : false,
      "numeric_detection" : true,
      "properties" : {
        "someDate" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "someNumber" : {
          "type" : "long"
        }
      }
    }
  }
}
// settings
{
  "testtemplate" : {
    "settings" : {
      "index" : {
        "creation_date" : "1684893022481",
        "number_of_shards" : "1",
        "number_of_replicas" : "2",
        "uuid" : "ZpqS8MJhStabGV5SuIjl7w",
        "version" : {
          "created" : "7010099"
        },
        "provided_name" : "testtemplate"
      }
    }
  }
}

插入自我配置的数据

PUT testmy
{
	"settings":{
		"number_of_replicas":5
	}
}

put testmy/_doc/1
{
  "key":"value"
}

get testmy/_settings

{
  "testmy" : {
    "settings" : {
      "index" : {
        "creation_date" : "1684893154540",
        "number_of_shards" : "1",
        "number_of_replicas" : "5",
        "uuid" : "6DgFXdp6S8-XwVuqAQV-PQ",
        "version" : {
          "created" : "7010099"
        },
        "provided_name" : "testmy"
      }
    }
  }
}

二、Dynamic Template

1、概念

由于Dynamic Mapping会自动根据自动根据文档信息，推算出字段的类型，我们可以设定Dynamic Template来设定Elasticsearch识别的数据类型，结合字段名称，来动态设定字段的类型：

• is开头的都设置为boolean。
• long_开头的都设置为long类型。
• 所有的字符串类型都设定成keyword。

2、案例实践

Dynamic Mapping自动推断

DELETE my_index

PUT my_index/_doc/1
{
  "firstName":"Ruan",
  "isVIP":"true"
}

GET my_index/_mapping
DELETE my_index

{
  "my_index" : {
    "mappings" : {
      "properties" : {
        "firstName" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "isVIP" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        }
      }
    }
  }
}

设定Dynamic Template

PUT my_index
{
  "mappings": {
    "dynamic_templates": [
            {
        "strings_as_boolean": {
          "match_mapping_type":   "string",
          "match":"is*",
          "mapping": {
            "type": "boolean"
          }
        }
      },
      {
        "strings_as_keywords": {
          "match_mapping_type":   "string",
          "mapping": {
            "type": "keyword"
          }
        }
      }
    ]
  }
}

PUT my_index/_doc/1
{
  "firstName":"Ruan",
  "isVIP":"true"
}

GET my_index/_mapping

{
  "my_index" : {
    "mappings" : {
      "dynamic_templates" : [
        {
          "strings_as_boolean" : {
            "match" : "is*",
            "match_mapping_type" : "string",
            "mapping" : {
              "type" : "boolean"
            }
          }
        },
        {
          "strings_as_keywords" : {
            "match_mapping_type" : "string",
            "mapping" : {
              "type" : "keyword"
            }
          }
        }
      ],
      "properties" : {
        "firstName" : {
          "type" : "keyword"
        },
        "isVIP" : {
          "type" : "boolean"
        }
      }
    }
  }
}

参考

Elasticsearch 核心技术与实战 (opens new window)