安装

https://www.elastic.co/downloads/past-releases/elasticsearch-7-17-0
下载完成启动bin/elasticsearch服务，可以在Postman调试各种请求。

基本语法

索引

创建索引

PUT: http://127.0.0.1:9200/shoppingResponse:
{"acknowledged": true,"shards_acknowledged": true,"index": "shopping"
}

多次创建同一个索引时，会报错，说明创建请求是幂等性的（同一个操作执行多次和执行一次效果相同，不会因为多次执行而产生不同的效果）。所以应该用PUT而非POST，POST每次都会创建一条新的记录，对于同一个请求，并不会由于索引重复而报错。

查看索引

GET: http://127.0.0.1:9200/shopping

包含了每个索引的健康状况、状态、名称、唯一ID（UUID）、分片数（primary和replica）、包含的文档数、删除的文档数、以及存储大小所有主分片占用的物理磁盘空间总。

删除索引

DELETE: http://127.0.0.1:9200/shopping

文档

创建文档

POST: http://127.0.0.1:9200/shopping/_doc`或者`POST: http://127.0.0.1:9200/shopping/_createRequest body:
{"name": "xiaomi su7","type": 1,"price": 29.99
}Response:
{"_index": "shopping","_type": "_doc","_id": "bhajbY8BDgHLWJjh9Xp7","_version": 1,"result": "created","_shards": {"total": 2,"successful": 1,"failed": 0},"_seq_no": 1,"_primary_term": 1
}

如果觉得id不好记忆，可以指定id创建文档：POST/PUT: http://127.0.0.1:9200/shopping/_doc/1001，重复调用会更新文档，如果明确用_create，重复调用会有冲突。

更新文档

POST: http://127.0.0.1:9200/shopping/_update/1001Request body:
{"doc": {"compony": "xiaomi "}
}Response：
{"_index": "shopping","_type": "_doc","_id": "1001","_version": 9,"result": "updated","_shards": {"total": 2,"successful": 1,"failed": 0},"_seq_no": 10,"_primary_term": 1
}

如果加上doc就是增量更新，否则为全亮更新。

匹配查询

GET: http://127.0.0.1:9200/shopping/_searchRequest Body:
{"query": {"match_all": {}/**"match": {"compony": "xiaomi"}*/"from": 0,"size": 2,"_source": ["type", "price"],"sort": {"price": {"order": "desc"}}
}Response:
{"took": 8,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 4,"relation": "eq"},"max_score": null,"hits": [{"_index": "shopping","_type": "_doc","_id": "1003","_score": null,"_source": {"price": 39.99,"type": 1},"sort": [39.99]},{"_index": "shopping","_type": "_doc","_id": "bhajbY8BDgHLWJjh9Xp7","_score": null,"_source": {"price": 29.99,"type": 1},"sort": [29.99]}]}
}

多条件查询

GET: http://127.0.0.1:9200/shopping/_searchRequest Body:
{"query": {"bool": {// 数组里的条件同时满足"must": [{"match": {"name": "xiaomi su7"}},{"match": {"type": 1}}],// 数组里的条件满足一个即可"should": [{"match": {"price": 39.99}}],// 对结果进行范围过滤"filter": {"range": {"price": {"gt": 30}}}}}
}Response:
{"took": 9,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 1,"relation": "eq"},"max_score": 2.2391143,"hits": [{"_index": "shopping","_type": "_doc","_id": "1003","_score": 2.2391143,"_source": {"name": "xiaomi su7 pro","type": 1,"price": 39.99}}]}
}

match 是分词检索，doc在存储的时候是倒排索引，会把里面的字段按空格（实验结果）拆成一些词，每个词都会对应一条id的数据。默认查询时用的并不是全词匹配，比如：

{"query": {"match": {"name": "su7"}}
}

能匹配到name = "xiaomi su7" / "xiaomi su7 pro" 的数据。

聚合查询

GET: http://127.0.0.1:9200/shopping/_searchRequest Body:
{"aggs": {"price_group": {"terms": { // 分组"field": "price"}}},"size": 0
}Response:
{"took": 15,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 4,"relation": "eq"},"max_score": null,"hits": []},"aggregations": {"price_group": {"doc_count_error_upper_bound": 0,"sum_other_doc_count": 0,"buckets": [{"key": 29.989999771118164,"doc_count": 2},{"key": 39.9900016784668,"doc_count": 1}]}}
}

映射

可以为某个索引设置一些映射的字段，包括字段是否能用分词查询（否则全亮匹配）、是否能用来查询。

PUT: http://127.0.0.1:9200/user/_mappingRequest Body:
{"properties": {"name": {"type": "text", // 可分词查询"index": true.  // 可作为查询字段   },"sex": {"type": "keyword", // 只能全亮匹配"index": true},"tel": {"type": "keyword","index": false     // 不可作为查询字段}}
}