45、初识搜索引擎_手动建立和修改mapping以及定制string类型数据是否分词

1、如何建立索引

• analyzed: full text 会建立倒排索引

• not_analyzed：不会建立倒排索引，走的是 exact value 搜索

• no：不走索引

2、修改 mapping

只能创建index时手动建立mapping，或者新增field mapping，但是不能update field mapping
创建 index 时，手动创建索引：

PUT /website
{
  "mappings": {
    "_doc": {
      "properties": {
        "author_id": {
          "type": "long"
        },
        "title": {
          "type": "text",
          "analyzer": "english"
        },
        "content": {
          "type": "text"
        },
        "post_date": {
          "type": "date"
        },
        "publisher_id": {
          "type": "text",
          "index": "not_analyzed"
        }
      }
    }
  }
}

报错：

{
  "error" : {
    "root_cause" : [
      {
        "type" : "illegal_argument_exception",
        "reason" : "The mapping definition cannot be nested under a type [_doc] unless include_type_name is set to true."
      }
    ],
    "type" : "illegal_argument_exception",
    "reason" : "The mapping definition cannot be nested under a type [_doc] unless include_type_name is set to true."
  },
  "status" : 400
}

出现这个的原因是，elasticsearch7默认不在支持指定索引类型，默认索引类型是_doc，如果想改变，则配置include_type_name: true 即可(这个没有测试，官方文档说的，无论是否可行，建议不要这么做，因为elasticsearch8后就不在提供该字段)。
改为如下：

PUT /newwebsite
{
  "mappings": {
      "properties":{
        "author_id": {
          "type": "long"
        },
        "content": {
          "type": "text",
          "analyzer": "english"
        },
        "title": {
          "type": "text"
        },
        "post_date": {
          "type": "date"
        },
        "publisher_id": {
          "type": "text",
          "index": "not_analyzed"
        }
      }
  }
}

报错：

{
  "error" : {
    "root_cause" : [
      {
        "type" : "mapper_parsing_exception",
        "reason" : "Failed to parse mapping [_doc]: Could not convert [publisher_id.index] to boolean"
      }
    ],
    "type" : "mapper_parsing_exception",
    "reason" : "Failed to parse mapping [_doc]: Could not convert [publisher_id.index] to boolean",
    "caused_by" : {
      "type" : "illegal_argument_exception",
      "reason" : "Could not convert [publisher_id.index] to boolean",
      "caused_by" : {
        "type" : "illegal_argument_exception",
        "reason" : "Failed to parse value [not_analyzed] as only [true] or [false] are allowed."
      }
    }
  },
  "status" : 400
}

index这个只能用true或者false了，如果想要不被分词就把数据类型设置为keyword
解决如下：

PUT /newwebsite
{
  "mappings": {
      "properties":{
        "author_id": {
          "type": "long"
        },
        "content": {
          "type": "text",
          "analyzer": "english"
        },
        "title": {
          "type": "text"
        },
        "post_date": {
          "type": "date"
        },
        "publisher_id": {
          "type": "keyword"
        }
      }
  }
}

{
  "acknowledged" : true,
  "shards_acknowledged" : true,
  "index" : "newwebsite"
}

更新字段的数据类型：

PUT /newwebsite
{
  "mappings": {
      "properties": {
        "author_id": {
          "type": "text"
        }
      }
  }
}

结果报错：

{
  "error" : {
    "root_cause" : [
      {
        "type" : "resource_already_exists_exception",
        "reason" : "index [newwebsite/Ym0xShwxQ1iChJuxNrjqRA] already exists",
        "index_uuid" : "Ym0xShwxQ1iChJuxNrjqRA",
        "index" : "newwebsite"
      }
    ],
    "type" : "resource_already_exists_exception",
    "reason" : "index [newwebsite/Ym0xShwxQ1iChJuxNrjqRA] already exists",
    "index_uuid" : "Ym0xShwxQ1iChJuxNrjqRA",
    "index" : "newwebsite"
  },
  "status" : 400
}

向 index 添加需要创建 mapping 的 field :

PUT /newwebsite/_mapping
{
  "properties" : {
    "new_field" : {
      "type" :    "string",
      "index":    false
    }
  }
}

报错如下：

{
  "error" : {
    "root_cause" : [
      {
        "type" : "mapper_parsing_exception",
        "reason" : "No handler for type [String] declared on field [new_field]"
      }
    ],
    "type" : "mapper_parsing_exception",
    "reason" : "No handler for type [String] declared on field [new_field]"
  },
  "status" : 400
}

报错原因

我使用的Elasticsearch是6.2.2版本，按照学习文档创建字段时，使用了{"type":"string","index":"not_analyzed"}。

原因分析

检查拼写无误之后，我决定去查Elasticsearch新版本特性，因为之前也踩过head插件的安装方法的坑，就是因为版本问题。
果不其然，Elasticsearch从5.X就引入了text和keyword，其中keyword适用于不分词字段，搜索时只能完全匹配，这时string还保留着。
到了6.X就彻底移除string了。
另外，”index”的值只能是boolean变量了。

解决方法

{"type":"text","index":false}

案例：

PUT /newwebsite/_mapping
{
  "properties" : {
    "new_field" : {
      "type": "text",
      "index": false
    }
  }
}

3、测试mapping

查看 content 字段的分词结果：

GET /newwebsite/_analyze
{
  "field": "content",
  "text": "my-dogs" 
}

查看 new_field 字段的分词结果：

GET /newwebsite/_analyze
{
  "field": "new_field",
  "text": "my dogs"
}

由于 new_field 的 index 配置为 not_analyzed 所以不走可以分词：

{
  "error": {
    "root_cause": [
      {
        "type": "remote_transport_exception",
        "reason": "[4onsTYV][127.0.0.1:9300][indices:admin/analyze[s]]"
      }
    ],
    "type": "illegal_argument_exception",
    "reason": "Can't process field [new_field], Analysis requests are only supported on tokenized fields"
  },
  "status": 400
}

ES7.x 中没有 not_analyzed