Elasticsearch查询上下文和_source

查询上下文

{"took": 1,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 1,"relation": "eq"},"max_score": 1,"hits": [{"_index": "user","_id": "1","_score": 1,"_source": {"name": "admin","age": 18,"firends": ["小明","小白","小吕"],"owner": {"name": "desc"}}}]}
}

1. took:查询时间，毫秒
2. time_out:是否超时
3. _shards:当前请求的分片
4. total:分片数量
5. successful:成功数量
6. skipped:跳过数量
7. failed:失败数量
8. hits:查询结果
9. total：
   1. value:查询结果条数
   2. relation:查询方式 如“eq"等于
   3. max_score:相关度评分
   4. hits:当前返回的结果
      1. _index:数据属于的索引
      2. _type:ES7.0后为_doc
      3. _id：当前数据id
      4. _score:当前数据相关度评分
      5. _source:元数据

相关度评分

在查询时候，如果不指定排序字段，默认使用相关度评分排序，评分度越高排名越靠前。

元数据

类似于mysql中的查询字段，*表示查询所有数据，相当于：

get user/_search
{"query":{"match_all":{}}
}

禁用元数据

1. 查询时候禁用元数据：

get user/_search
{"_source":false,"query":{"match_all":{}}
}

结果：hits中只包含id

{"took": 12,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 1,"relation": "eq"},"max_score": 1,"hits": [{"_index": "user","_id": "1","_score": 1}]}
}

2. 使用Mapping禁用元数据：通过includes指定要查询的字段，excludes指定不查询的字段，excludes优先级高于includes,不推荐使用，因为mapping创建后不能修改。

put user2
{"mappings": {"_source": {"includes": ["name","age"],"excludes": ["firends","owner"]}}
}
put user2/_doc/1
{"name":"admin","age":18,"firends":["小明","小白","小吕"],"owner":{"name":"desc"}
}
get user2/_search

结果：

{"took": 0,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 1,"relation": "eq"},"max_score": 1,"hits": [{"_index": "user2","_id": "1","_score": 1,"_source": {"name": "admin","age": 18}}]}
}

查询时候_source的使用

和Mysql中的select指定查询的字段作用一样

1. 可使用通配符

get user/_search
{"_source": "owner.*","query":{"match_all": {}}
}

结果：

{"took": 1,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 1,"relation": "eq"},"max_score": 1,"hits": [{"_index": "user","_id": "1","_score": 1,"_source": {"owner": {"name": "desc","other": "other"}}}]}
}

2. 使用includes和excludes

get user/_search
{"_source":{"includes":["name","owener.name"],"excludes":["age"]},"query":{"match_all": {}}
}

结果：

{"took": 0,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 1,"relation": "eq"},"max_score": 1,"hits": [{"_index": "user","_id": "1","_score": 1,"_source": {"name": "admin"}}]}
}

3. 禁用_source

get user/_search
{"_source":false,"query":{"match_all":{}}
}

query_string查询

1. 查询所有

get /user/_search

2. 带参查询

get /user/_search?p=name:admin

3. 分页查询

get /user/_search?from=0&size=2&sort=age:asc

4. 精准匹配

get /user/_search?q=date=2024-06-29

5. _all查询，在所有的有索引的字段中匹配

get /user/_search?q=2024-06-29

注意：

1. 第4种查询是精准匹配，只会匹配date字段
2. 第5种查询是全文匹配，会匹配所有有索引的字段
3. 如果执行 get /user/_searct?q=2024,则date类型的字段不会被检索，因为date类型只支持精准匹配