Elasticsearch 7：索引模板

#Elasticsearch

介绍

在新建索引/自动新建索引时，若索引名符合索引模板的条件，则会按照模板创建模板。

相关官方文档：

• https://www.elastic.co/guide/en/elasticsearch/reference/current/index-templates.html
• https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-templates-v1.html

命令示例

查询所有模板信息：

GET _index_template

查询指定模板信息：

GET _index_template/template_1

GET _index_template/template*

删除模板：

DELETE /_index_template/template_1

操作实战1：基础示例

创建模板，匹配 stu 开头的索引：

PUT /_index_template/template_1
{
  "index_patterns" : ["stu*"],
  "template": {
    "mappings" : {
      "properties" : {
        "name" : { "type" : "keyword" },
        "age" : { "type" : "integer" }
      }
    },
    "settings" : {
      "number_of_shards" : 2
    }
  }
}

查询所有模板信息：

GET _index_template

创建索引时会自动匹配模板：

# 创建索引
PUT student

# 查询索引结构
GET student
# 查询结果
{
  "student" : {
    "aliases" : { },
    "mappings" : {
      "properties" : {
        "age" : {
          "type" : "integer"
        },
        "name" : {
          "type" : "keyword"
        }
      }
    },
    "settings" : {
        
      "index" : {
        "routing" : {
          "allocation" : {
            "include" : {
              "_tier_preference" : "data_content"
            }
          }
        },
        "number_of_shards" : "2",
        "provided_name" : "student",
        "creation_date" : "1634356238830",
        "number_of_replicas" : "1",
        "uuid" : "DiR_5wuNQEqoMjVzRXN_RQ",
        "version" : {
          "created" : "7150099"
        }
      }
    }
  }
}

如果创建索引时，指定的部分数据属性和配置，则优先使用。命中的模板会作为补充： ​

PUT student_2
{
  "mappings" : {
    "properties" : {
      "name" : {
        "type" : "text"
      },
      "height" : {
        "type" : "long"
      }
    }
  },
  "settings" : {
    "index" : {
      "number_of_shards" : 1,
      "number_of_replicas" : 2
    }
  }
}


# 查询索引结构
GET student_2
# 查询结果
{
  "student_2" : {
    "aliases" : { },
    "mappings" : {
      "properties" : {
        "age" : {
          "type" : "integer"   # 通过模板增加该字段
        },
        "height" : {
          "type" : "long"
        },
        "name" : {
          "type" : "text"
        }
      }
    },
    "settings" : {
      "index" : {
        "routing" : {
          "allocation" : {
            "include" : {
              "_tier_preference" : "data_content"
            }
          }
        },
        "number_of_shards" : "1",   // 没有使用模板指定的2
        "provided_name" : "student_2",
        "creation_date" : "1634518830185",
        "number_of_replicas" : "2",
        "uuid" : "QD9n3uPcSiud4d3fqayZOg",
        "version" : {
          "created" : "7150099"
        }
      }
    }
  }
}

删除模板：

# 请求
DELETE /_index_template/template_1

# 响应
{
  "acknowledged" : true
}

操作实战2：模板优先级

如果索引名，匹配了两个模板，会如何？ ​

我们创建两个模板：

PUT /_index_template/template_1
{
  "index_patterns" : ["stu*"],
  "template": {
    "mappings" : {
      "properties" : {
        "name" : { "type" : "keyword" },
        "age" : { "type" : "integer" }
      }
    },
    "settings" : {
      "number_of_shards" : 2
    }
  }
}

PUT /_index_template/template_2
{
  "index_patterns" : ["stud*"],
  "template": {
    "mappings" : {
      "properties" : {
        "age" : { "type" : "long" },
        "height" : { "type" : "long" }
      }
    },
    "settings" : {
      "number_of_shards" : 3
    }
  }
}

// 报错如下：
{
  "error" : {
    "root_cause" : [
      {
        "type" : "illegal_argument_exception",
        "reason" : "index template [template_2] has index patterns [stud*] matching patterns from existing templates [template_1] with patterns (template_1 => [stu*]) that have the same priority [0], multiple index templates may not match during index creation, please use a different priority"
      }
    ],
    "type" : "illegal_argument_exception",
    "reason" : "index template [template_2] has index patterns [stud*] matching patterns from existing templates [template_1] with patterns (template_1 => [stu*]) that have the same priority [0], multiple index templates may not match during index creation, please use a different priority"
  },
  "status" : 400
}

如果 index_patterns 有相同的前缀，要指定 **priority** 。**priority**** 默认值为0，代表最低优先级。创建索引时，使用最高优先级的模板。** ​

下面的方式创建，则没有问题：

PUT /_index_template/template_2
{
  "index_patterns" : ["stud*"],
  "priority": 1,
  "template": {
    "mappings" : {
      "properties" : {
        "age" : { "type" : "long" },
        "height" : { "type" : "long" }
      }
    },
    "settings" : {
      "number_of_shards" : 3
    }
  }
}

创建索引：

PUT student

查询索引结构： ​

{
  "student" : {
    "aliases" : { },
    "mappings" : {
      "properties" : {
        "age" : {
          "type" : "long"
        },
        "height" : {
          "type" : "long"
        }
      }
    },
    "settings" : {
      "index" : {
        "routing" : {
          "allocation" : {
            "include" : {
              "_tier_preference" : "data_content"
            }
          }
        },
        "number_of_shards" : "3",
        "provided_name" : "student",
        "creation_date" : "1634606600477",
        "number_of_replicas" : "1",
        "uuid" : "6tjI9CKAQGWGKpA3a1NFKQ",
        "version" : {
          "created" : "7150099"
        }
      }
    }
  }
}

操作实例3：更新索引/仅创建索引

使用 PUT /_index_template/<template_name> 时，若之前模板已存在则会覆盖。 使用 PUT /_index_template/<template_name>?create 时，若之前模板已存在则会报错。 ​

示例：

# 创建
PUT /_index_template/template_1
{
  "index_patterns" : ["stu*"],  # 匹配 stu 开头的索引
  "template": {
    "mappings" : {
      "properties" : {
        "name" : { "type" : "keyword" },
        "age" : { "type" : "integer" }  # 类型是 integer
      }
    },
    "settings" : {
      "number_of_shards" : 2
    }
  }
}

GET /_index_template/template_1
# 查询结果：
{
  "index_templates" : [
    {
      "name" : "template_1",
      "index_template" : {
        "index_patterns" : [
          "stu*"
        ],
        "template" : {
          "settings" : {
            "index" : {
              "number_of_shards" : "2"
            }
          },
          "mappings" : {
            "properties" : {
              "name" : {
                "type" : "keyword"
              },
              "age" : {
                "type" : "integer"
              }
            }
          }
        },
        "composed_of" : [ ]
      }
    }
  ]
}

# 再次创建
PUT /_index_template/template_1
{
  "index_patterns" : ["stud*"],      # 匹配  stud 开头的索引
  "template": {
    "mappings" : {
      "properties" : {
        "name" : { "type" : "keyword" },
        "age" : { "type" : "long" }  # 类型是 long ，和之前不一样
      }
    },
    "settings" : {
      "number_of_shards" : 2
    }
  }
}

// 再次查看
GET /_index_template/template_1

// 查询结果
{
  "index_templates" : [
    {
      "name" : "template_1",
      "index_template" : {
        "index_patterns" : [
          "stud*"
        ],
        "template" : {
          "settings" : {
            "index" : {
              "number_of_shards" : "2"
            }
          },
          "mappings" : {
            "properties" : {
              "name" : {
                "type" : "keyword"
              },
              "age" : {
                "type" : "long"
              }
            }
          }
        },
        "composed_of" : [ ]
      }
    }
  ]
}

// 追加 ?create 参数创建索引
PUT /_index_template/template_1?create
{
  "index_patterns" : ["stud*"],
  "template": {
    "mappings" : {
      "properties" : {
        "name" : { "type" : "keyword" },
        "age" : { "type" : "long" }
      }
    },
    "settings" : {
      "number_of_shards" : 2
    }
  }
}

# 会报错如下：

{
  "error" : {
    "root_cause" : [
      {
        "type" : "illegal_argument_exception",
        "reason" : "index template [template_1] already exists"
      }
    ],
    "type" : "illegal_argument_exception",
    "reason" : "index template [template_1] already exists"
  },
  "status" : 400
}

组合模板

从 ES 7.8 引入了组合模板。 具体可以参考：https://www.elastic.co/guide/en/elasticsearch/reference/current/index-templates.html

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