ES快速上手

如果你像我开始一样好奇ElasticSearch究竟能干什么？那么文章可能适合你看看。本文对ElasticSearch做一个简介及快速上手，主要例子来源于官网。

本文只需要你安装有docker、可发送curl请求即可操作。

二话不说，先在本地通过docker搭建一个可访问的ElasticSearch服务（以下简称ES）

docker安装ES

docker network create elastic
docker pull docker.elastic.co/elasticsearch/elasticsearch:7.17.3
docker run --name es01-test --net elastic -p 127.0.0.1:9200:9200 -p 127.0.0.1:9300:9300 -e "discovery.type=single-node" docker.elastic.co/elasticsearch/elasticsearch:7.17.3

如果你希望一个可视化操作，可以通过Kibana，本文不做详细介绍，一切从简。

员工文档业务需求：

1.支持包含多值标签、数值、以及全文本的数据
2.检索任一员工的完整信息
3.允许结构化搜索，比如查询30岁以上的员工
4.允许简单的全文搜索以及较复杂的短语搜索
5.支持在匹配文档内容中高亮显示搜索片段
6.支持基于数据创建和管理分析仪表盘（本文不做支持）

介绍

对于员工目录，我们将做如下操作：
1.每个员工索引一个文档，文档包含该员工的所有信息。
2.每个文档都将是 employee 类型。
3.该类型位于索引 megacorp 内。

剩下的操作只需要通过curl来请求ES，在终端执行curl即可开始访问。

1.添加单个员工

curl -X PUT "localhost:9200/megacorp/employee/1?pretty" -H 'Content-Type: application/json' -d'
{
    "first_name" : "John",
    "last_name" :  "Smith",
    "age" :        25,
    "about" :      "I love to go rock climbing",
    "interests": [ "sports", "music" ]
}
'

2.添加多个员工

curl -X PUT "localhost:9200/megacorp/employee/2?pretty" -H 'Content-Type: application/json' -d'
{
    "first_name" :  "Jane",
    "last_name" :   "Smith",
    "age" :         32,
    "about" :       "I like to collect rock albums",
    "interests":  [ "music" ]
}
'
curl -X PUT "localhost:9200/megacorp/employee/3?pretty" -H 'Content-Type: application/json' -d'
{
    "first_name" :  "Douglas",
    "last_name" :   "Fir",
    "age" :         35,
    "about":        "I like to build cabinets",
    "interests":  [ "forestry" ]
}
'

// 请求
curl -X GET "localhost:9200/megacorp/employee/1?pretty"

// 返回
{
  "_index" : "megacorp",
  "_type" : "employee",
  "_id" : "1",
  "_version" : 1,
  "_seq_no" : 0,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "first_name" : "John",
    "last_name" : "Smith",
    "age" : 25,
    "about" : "I love to go rock climbing",
    "interests" : [
      "sports",
      "music"
    ]
  }
}

3.查询全部员工

// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?pretty"

// 返回
{
  "took" : 324,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 3,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "first_name" : "John",
          "last_name" : "Smith",
          "age" : 25,
          "about" : "I love to go rock climbing",
          "interests" : [
            "sports",
            "music"
          ]
        }
      },
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "first_name" : "Jane",
          "last_name" : "Smith",
          "age" : 32,
          "about" : "I like to collect rock albums",
          "interests" : [
            "music"
          ]
        }
      },
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "3",
        "_score" : 1.0,
        "_source" : {
          "first_name" : "Douglas",
          "last_name" : "Fir",
          "age" : 35,
          "about" : "I like to build cabinets",
          "interests" : [
            "forestry"
          ]
        }
      }
    ]
  }
}

4.带条件查询

// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?q=last_name:Smith&pretty"

// 返回
{
  "took" : 958,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 0.4700036,
    "hits" : [
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "1",
        "_score" : 0.4700036,
        "_source" : {
          "first_name" : "John",
          "last_name" : "Smith",
          "age" : 25,
          "about" : "I love to go rock climbing",
          "interests" : [
            "sports",
            "music"
          ]
        }
      },
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "2",
        "_score" : 0.4700036,
        "_source" : {
          "first_name" : "Jane",
          "last_name" : "Smith",
          "age" : 32,
          "about" : "I like to collect rock albums",
          "interests" : [
            "music"
          ]
        }
      }
    ]
  }
}

5.使用查询表达式搜索

// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "match" : {
            "last_name" : "Smith"
        }
    }
}
'
// 返回 (同例4)

6.复杂查询

curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "bool": {
            "must": {
                "match" : {
                    "last_name" : "smith" 
                }
            },
            "filter": {
                "range" : {
                    "age" : { "gt" : 30 } 
                }
            }
        }
    }
}
'

7.关联查询

curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "match" : {
            "about" : "rock climbing"
        }
    }
}
'

8.短语查询

curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "match_phrase" : {
            "about" : "rock climbing"
        }
    }
}
'

9.1聚合

// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
  "aggs": {
    "all_interests": {
      "terms": { "field": "interests.keyword" }
    }
  }
}
'

// 返回
{
  "took" : 454,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 3,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "first_name" : "John",
          "last_name" : "Smith",
          "age" : 25,
          "about" : "I love to go rock climbing",
          "interests" : [
            "sports",
            "music"
          ]
        }
      },
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "first_name" : "Jane",
          "last_name" : "Smith",
          "age" : 32,
          "about" : "I like to collect rock albums",
          "interests" : [
            "music"
          ]
        }
      },
      {
        "_index" : "megacorp",
        "_type" : "employee",
        "_id" : "3",
        "_score" : 1.0,
        "_source" : {
          "first_name" : "Douglas",
          "last_name" : "Fir",
          "age" : 35,
          "about" : "I like to build cabinets",
          "interests" : [
            "forestry"
          ]
        }
      }
    ]
  },
  "aggregations" : {
    "all_interests" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "music",
          "doc_count" : 2
        },
        {
          "key" : "forestry",
          "doc_count" : 1
        },
        {
          "key" : "sports",
          "doc_count" : 1
        }
      ]
    }
  }
}

9.2 聚合+条件

curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
  "query": {
    "match": {
      "last_name": "smith"
    }
  },
  "aggs": {
    "all_interests": {
      "terms": {
        "field": "interests.keyword"
      }
    }
  }
}
'

9.3 聚合+结果

curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "all_interests" : {
            "terms" : { "field" : "interests.keyword" },
            "aggs" : {
                "avg_age" : {
                    "avg" : { "field" : "age" }
                }
            }
        }
    }
}
'

相信一通操作下来就有点感觉了，和Mysql的insert、select可以对比一下，当然目前为止这还只是ES最简单的套路。

总结

本文通过docker运行es，并给出员工的例子进行了简单介绍。

Q1:再次运行docker run时遇到报错

docker: Error response from daemon: Conflict. The container name "/es01-test" is already in use by container "414ad17fb21a8a0ac7295bda1440a5646a92110f7f9ed94c5dcfd291d8213d64". You have to remove (or rename) that container to be able to reuse that name.

解决：docker rm es01-test删除镜像后重新操作即可。

Reference

ES快速上手：https://www.elastic.co/guide/en/elasticsearch/reference/7.17/getting-started.html#getting-started
ES权威指南：https://www.elastic.co/guide/cn/elasticsearch/guide/current/index.html 章节《你知道的, 为了搜索…》

ES快速上手

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