ElasticSearch中的映射（mapping）

前面博客中创建的索引以及插入数据，都是由Elasticsearch进行自动判断类型，有些时候是需要进行明确字段类型的，否则，自动判断的类型和实际需求有时候是不相符的。

自动判断的规则如下：

JSON type	Field type
Boolean: true or false	"boolean"
Whole number: 123	"long"
Floating point: 123.45	"double"
String, valid date: "2014-09-15"	"date"
String: "foo bar"	"string"

Elasticsearch中支持的类型如下：

类型	表示的数据类型
String	string , text , keyword
Whole number	byte , short , integer , long
Floating point	float , double
Boolean	boolean
Date	date

注意：

string类型在ElasticSearch 旧版本中使用较多，从ElasticSearch 5.x开始不再支持string，由text和 keyword类型替代。
text 类型，当一个字段是要被全文搜索的，比如Email内容、产品描述，应该使用text类型。设置text类型以后，字段内容会被分析，在生成倒排索引以前，字符串会被分析器分成一个一个词项。text类型的字段不用于排序，很少用于聚合。
keyword类型适用于索引结构化的字段，比如email地址、主机名、状态码和标签。如果字段需要进行过滤(比如查找已发布博客中status属性为published的文章)、排序、聚合。keyword类型的字段只能通过精确值搜索到。

创建明确类型的索引：

PUT /study
# 请求数据
{"settings": {"index": {"number_of_shards": "2","number_of_replicas": "0"}},"mappings": {"properties": {"name": {"type": "text"},"age": {"type": "integer"},"mail": {"type": "keyword"},"hobby": {"type": "text"}}}
}# 响应数据
{"acknowledged": true,"shards_acknowledged": true,"index": "study"
}

这儿可能存在的错误，参考博文：ElasticSearch 7.x 报错：Root mapping definition has unsupported parameters_Sunny Feng的博客-CSDN博客

查看映射：

GET /study/_mapping# 响应数据
{"study": {"mappings": {"properties": {"age": {"type": "integer"},"hobby": {"type": "text"},"mail": {"type": "keyword"},"name": {"type": "text"}}}}
}

插入数据：

POST  /study/_bulk
# 请求数据
{"index":{"_index":"study"}} 
{"name":"张三","age": 20,"mail": "111@qq.com","hobby":"羽毛球、乒乓球、足球"} 
{"index":{"_index":"study"}} 
{"name":"李四","age": 21,"mail": "222@qq.com","hobby":"羽毛球、乒乓球、足球、篮球"} 
{"index":{"_index":"study"}} 
{"name":"王五","age": 22,"mail": "333@qq.com","hobby":"羽毛球、篮球、游泳、听音乐"} 
{"index":{"_index":"study"}} 
{"name":"赵六","age": 23,"mail": "444@qq.com","hobby":"跑步、游泳"} 
{"index":{"_index":"study"}} 
{"name":"孙七","age": 24,"mail": "555@qq.com","hobby":"听音乐、看电影"}# 响应结果
{"took": 25,"errors": false,"items": [{"index": {"_index": "study","_type": "_doc","_id": "SHjOVIIBpyNh4YQ4CVSN","_version": 1,"result": "created","_shards": {"total": 1,"successful": 1,"failed": 0},"_seq_no": 0,"_primary_term": 1,"status": 201}},{"index": {"_index": "study","_type": "_doc","_id": "SXjOVIIBpyNh4YQ4CVSN","_version": 1,"result": "created","_shards": {"total": 1,"successful": 1,"failed": 0},"_seq_no": 0,"_primary_term": 1,"status": 201}},{"index": {"_index": "study","_type": "_doc","_id": "SnjOVIIBpyNh4YQ4CVSN","_version": 1,"result": "created","_shards": {"total": 1,"successful": 1,"failed": 0},"_seq_no": 1,"_primary_term": 1,"status": 201}},{"index": {"_index": "study","_type": "_doc","_id": "S3jOVIIBpyNh4YQ4CVSN","_version": 1,"result": "created","_shards": {"total": 1,"successful": 1,"failed": 0},"_seq_no": 1,"_primary_term": 1,"status": 201}},{"index": {"_index": "study","_type": "_doc","_id": "THjOVIIBpyNh4YQ4CVSN","_version": 1,"result": "created","_shards": {"total": 1,"successful": 1,"failed": 0},"_seq_no": 2,"_primary_term": 1,"status": 201}}]
}

注意：通过上面的数据库中数据可以看到，默认生成的是_doc类型的数据。

测试搜索：

POST /study/_search# 请求数据
{"query": {"match": {"hobby": "音乐"}}
}# 响应数据
{"took": 2,"timed_out": false,"_shards": {"total": 2,"successful": 2,"skipped": 0,"failed": 0},"hits": {"total": {"value": 2,"relation": "eq"},"max_score": 1.0470967,"hits": [{"_index": "study","_type": "_doc","_id": "THjOVIIBpyNh4YQ4CVSN","_score": 1.0470967,"_source": {"name": "孙七","age": 24,"mail": "555@qq.com","hobby": "听音乐、看电影"}},{"_index": "study","_type": "_doc","_id": "SnjOVIIBpyNh4YQ4CVSN","_score": 0.8527901,"_source": {"name": "王五","age": 22,"mail": "333@qq.com","hobby": "羽毛球、篮球、游泳、听音乐"}}]}
}