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