Elasticsearch 基本搜索

深碍√TFBOYSˉ_ 2021-12-05 05:21 379阅读 0赞

这里，我们主要介绍如何使用 Elasticsearch 进行一些基本的搜索操作。

首先，我们先向 alibaba/user 中新增 3 条记录。

PUT /alibaba/user/1
    {
        "email": "john@smith.com",
        "first_name": "John",
        "last_name": "Smith",
        "full_name": "John Smith",
        "info": {
            "age": 25,
            "interests": [ "games", "musics" ],
            "address": "guangdong shenzhen nanshan"
        },
        "created_at": "2019-06-06 08:30:10"
    }

PUT /alibaba/user/2
    {
        "email": "john2@smith.com",
        "first_name": "John2",
        "last_name": "Smith",
        "full_name": "John2 Smith",
        "info": {
            "age": 28,
            "interests": [ "games", "books" ],
            "address": "guangdong shenzhen baoan"
        },
        "created_at": "2019-06-07 08:30:10"
    }

PUT /alibaba/user/3
    {
        "email": "john3@smith.com",
        "first_name": "John3",
        "last_name": "Smith",
        "full_name": "John3 Smith",
        "info": {
            "age": 35,
            "interests": [ "sports", "musics" ],
            "address": "guangdong shenzhen longhua"
        },
        "created_at": "2019-06-08 09:40:10"
    }

## 检索文档 ##

目前，在 alibaba 这个索引库中已经有了 3 条用户信息。假如，我们想要检索 id 为 1 的用户信息。可以这样写：

GET /alibaba/user/1

返回结果：

{
      "_index": "alibaba",
      "_type": "user",
      "_id": "1",
      "_version": 1,
      "found": true,
      "_source": {
        "email": "john@smith.com",
        "first_name": "John",
        "last_name": "Smith",
        "full_name": "John Smith",
        "info": {
          "age": 25,
          "interests": [
            "games",
            "musics"
          ],
          "address": "guangdong shenzhen nanshan"
        },
        "created_at": "2019-06-06 08:30:10"
      }
    }

**返回结果的说明：**

*  \_index：索引库，相当于 MySQL 中的数据库。
 *  \_type：类型（分类），相当于 MySQL 中的数据表。
 *  \_id：文档（记录）的 id，可以为字符串。
 *  \_version：文档的版本，初始值为 1。
 *  found：是否查询成功，true 成功，false 失败。
 *  \_source： 文档的原始数据，它包含文档的所有字段。

我们通过 GET 来检索文档，同样的，我们可以使用 DELETE 方法删除文档，使用 HEAD 方法检查某文档是否存在。如果想更新已存在的文档，我们只需再 PUT 一次。

## 简单搜索 ##

如下，是一个最简单的搜索全部用户的请求：

GET /alibaba/user/_search

返回结果：

{
      "took": 1,
      "timed_out": false,
      "_shards": {
        "total": 5,
        "successful": 5,
        "failed": 0
      },
      "hits": {
        "total": 3,
        "max_score": 1,
        "hits": [
          {
            "_index": "alibaba",
            "_type": "user",
            "_id": "2",
            "_score": 1,
            "_source": {
              "email": "john2@smith.com",
              "first_name": "John2",
              "last_name": "Smith",
              "full_name": "John2 Smith",
              "info": {
                "age": 28,
                "interests": [
                  "games",
                  "books"
                ],
                "address": "guangdong shenzhen baoan"
              },
              "created_at": "2019-06-07 08:30:10"
            }
          },
          {
            "_index": "alibaba",
            "_type": "user",
            "_id": "1",
            "_score": 1,
            "_source": {
              "email": "john@smith.com",
              "first_name": "John",
              "last_name": "Smith",
              "full_name": "John Smith",
              "info": {
                "age": 25,
                "interests": [
                  "games",
                  "musics"
                ],
                "address": "guangdong shenzhen nanshan"
              },
              "created_at": "2019-06-06 08:30:10"
            }
          },
          {
            "_index": "alibaba",
            "_type": "user",
            "_id": "3",
            "_score": 1,
            "_source": {
              "email": "john3@smith.com",
              "first_name": "John3",
              "last_name": "Smith",
              "full_name": "John3 Smith",
              "info": {
                "age": 35,
                "interests": [
                  "sports",
                  "musics"
                ],
                "address": "guangdong shenzhen longhua"
              },
              "created_at": "2019-06-08 09:40:10"
            }
          }
        ]
      }
    }

**返回结果的说明：**

*  took：查询消耗的时间，单位：毫秒。
 *  timed\_out：查询是否超时。
 *  \_shards：描述了查询分片的信息，查询了多少个分片、成功的分片数、失败的分片数等。
 *  hits：搜索命中到的结果。其中，total 代表搜索到的文档总数；max\_score 代表文档的最大搜索排名分数；hits 数组代表搜索到的文档数组，默认会返回前 10 条记录。

## 查询字符串搜索 ##

例如，要搜索 first\_name 字段包含 John 的用户，可以这样写：

GET /alibaba/user/_search?q=first_name:John

我们像传递 URL 参数一样去传递查询语句，这种写法被称为查询字符串（query string）搜索。

返回结果：

{
      "took": 2,
      "timed_out": false,
      "_shards": {
        "total": 5,
        "successful": 5,
        "failed": 0
      },
      "hits": {
        "total": 1,
        "max_score": 0.2876821,
        "hits": [
          {
            "_index": "alibaba",
            "_type": "user",
            "_id": "1",
            "_score": 0.2876821,
            "_source": {
              "email": "john@smith.com",
              "first_name": "John",
              "last_name": "Smith",
              "full_name": "John Smith",
              "info": {
                "age": 25,
                "interests": [
                  "games",
                  "musics"
                ],
                "address": "guangdong shenzhen nanshan"
              },
              "created_at": "2019-06-06 08:30:10"
            }
          }
        ]
      }
    }

在下一节中，我们再来介绍 **DSL 查询语句**。