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ElasticSearch使用教程

Elasticsearch简介

Elasticsearch是一个基于Lucene的搜索服务器。它提供了一个分布式的全文搜索引擎,基于restful web接口。

Elasticsearch是用Java语言开发的,基于Apache协议的开源项目,是目前最受欢迎的企业搜索引擎。Elasticsearch广泛运用于云计算中,能够达到实时搜索,具有稳定,可靠,快速的特点。

Elasticsearch的安装

Windows下的安装

Elasticsearch

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  • 下载完成后解压到Elasticsearch的plugins目录下;

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  • 运行bin目录下的elasticsearch.bat启动Elasticsearch服务;

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  • 然后添加系统环境变量ES_JAVA_HOME,值为你的JDK 11解压路径即可解决。

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Kibana

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  • 运行bin目录下的kibana.bat,启动Kibana服务;

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Linux下的安装

Elasticsearch
  • 下载Elasticsearch7.17.3的docker镜像:
bash
docker pull elasticsearch:7.17.3
  • 修改虚拟内存区域大小,否则会因为过小而无法启动:
bash
sysctl -w vm.max_map_count=262144
  • 使用如下命令启动Elasticsearch服务,内存小的服务器可以通过ES_JAVA_OPTS来设置占用内存大小:
bash
docker run -p 9200:9200 -p 9300:9300 --name elasticsearch \
-e "discovery.type=single-node" \
-e "cluster.name=elasticsearch" \
-e "ES_JAVA_OPTS=-Xms512m -Xmx1024m" \
-v /mydata/elasticsearch/plugins:/usr/share/elasticsearch/plugins \
-v /mydata/elasticsearch/data:/usr/share/elasticsearch/data \
-d elasticsearch:7.17.3
  • 启动时会发现/usr/share/elasticsearch/data目录没有访问权限,只需要修改/mydata/elasticsearch/data目录的权限,再重新启动即可;
bash
chmod 777 /mydata/elasticsearch/data/

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  • 下载完成后解压到Elasticsearch的/mydata/elasticsearch/plugins目录下;

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  • 重新启动服务:
bash
docker restart elasticsearch
  • 开启防火墙:
bash
firewall-cmd --zone=public --add-port=9200/tcp --permanent
firewall-cmd --reload
json
{
  "name": "708f1d885c16",
  "cluster_name": "elasticsearch",
  "cluster_uuid": "mza51wT-QvaZ5R0NmE183g",
  "version": {
    "number": "7.17.3",
    "build_flavor": "default",
    "build_type": "docker",
    "build_hash": "5ad023604c8d7416c9eb6c0eadb62b14e766caff",
    "build_date": "2022-04-19T08:11:19.070913226Z",
    "build_snapshot": false,
    "lucene_version": "8.11.1",
    "minimum_wire_compatibility_version": "6.8.0",
    "minimum_index_compatibility_version": "6.0.0-beta1"
  },
  "tagline": "You Know, for Search"
}
Kibana
  • 下载Kibana7.17.3的docker镜像:
bash
docker pull kibana:7.17.3
  • 使用如下命令启动Kibana服务:
bash
docker run --name kibana -p 5601:5601 \
--link elasticsearch:es \
-e "elasticsearch.hosts=http://es:9200" \
-d kibana:7.17.3
  • 开启防火墙:
bash
firewall-cmd --zone=public --add-port=5601/tcp --permanent
firewall-cmd --reload

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相关概念

  • Near Realtime(近实时):Elasticsearch是一个近乎实时的搜索平台,这意味着从索引文档到可搜索文档之间只有一个轻微的延迟(通常是一秒钟)。
  • Cluster(集群):群集是一个或多个节点的集合,它们一起保存整个数据,并提供跨所有节点的联合索引和搜索功能。每个集群都有自己的唯一集群名称,节点通过名称加入集群。
  • Node(节点):节点是指属于集群的单个Elasticsearch实例,存储数据并参与集群的索引和搜索功能。可以将节点配置为按集群名称加入特定集群,默认情况下,每个节点都设置为加入一个名为elasticsearch的群集。
  • Index(索引):索引是一些具有相似特征的文档集合,类似于MySql中数据库的概念。
  • Type(类型):类型是索引的逻辑类别分区,通常,为具有一组公共字段的文档类型,类似MySql中表的概念。注意:在Elasticsearch 6.0.0及更高的版本中,一个索引只能包含一个类型。
  • Document(文档):文档是可被索引的基本信息单位,以JSON形式表示,类似于MySql中行记录的概念。
  • Shards(分片):当索引存储大量数据时,可能会超出单个节点的硬件限制,为了解决这个问题,Elasticsearch提供了将索引细分为分片的概念。分片机制赋予了索引水平扩容的能力、并允许跨分片分发和并行化操作,从而提高性能和吞吐量。
  • Replicas(副本):在可能出现故障的网络环境中,需要有一个故障切换机制,Elasticsearch提供了将索引的分片复制为一个或多个副本的功能,副本在某些节点失效的情况下提供高可用性。

集群状态查看

  • 通过Kibana的Dev Tools功能,我们可以操作Elasticsearch;

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  • 例如使用如下命令查看集群健康状态;
json
GET /_cat/health?v
  • 具体操作如下;

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  • 返回结果如下;
epoch      timestamp cluster       status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1669776576 02:49:36  elasticsearch yellow          1         1     21  21    0    0        7             0                  -                 75.0%
  • 查看节点状态;
json
GET /_cat/nodes?v
ip        heap.percent ram.percent cpu load_1m load_5m load_15m node.role   master name
127.0.0.1           16          64  34                          cdfhilmrstw *      DESKTOP-K1F7O7Q
  • 查看所有索引信息;
json
GET /_cat/indices?v
health status index                           uuid                   pri rep docs.count docs.deleted store.size pri.store.size
green  open   pms                             6cEV5X3FSYWlGEbLCsMpmg   1   0         57            0     24.3kb         24.3kb
green  open   .kibana_7.17.3_001              hrS91kWhQkajmrhF92zboQ   1   0        327          327      4.8mb          4.8mb
green  open   .tasks                          _4RSAkwvRwK-j8zDLAM6MA   1   0         12            0     22.5kb         22.5kb

索引操作

  • 创建索引并查看;
json
PUT /customer
GET /_cat/indices?v
health status index                           uuid                   pri rep docs.count docs.deleted store.size pri.store.size
green  open   pms                             6cEV5X3FSYWlGEbLCsMpmg   1   0         57            0     24.3kb         24.3kb
yellow open   customer                        mU0uITAkSaeEie8fypLnFw   1   1          0            0       226b           226b
green  open   .kibana_7.17.3_001              hrS91kWhQkajmrhF92zboQ   1   0        329          336      4.8mb          4.8mb
  • 删除索引并查看;
json
DELETE /customer
GET /_cat/indices?v
health status index                           uuid                   pri rep docs.count docs.deleted store.size pri.store.size
green  open   pms                             6cEV5X3FSYWlGEbLCsMpmg   1   0         57            0     24.3kb         24.3kb
green  open   .kibana_7.17.3_001              hrS91kWhQkajmrhF92zboQ   1   0        329          336      4.8mb          4.8mb

类型操作

查看文档的类型,需要完成数据搜索部分的导入才可以查看。

json
GET /bank/_mapping
json
{
  "bank" : {
    "mappings" : {
      "properties" : {
        "account_number" : {
          "type" : "long"
        },
        "address" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "age" : {
          "type" : "long"
        },
        "balance" : {
          "type" : "long"
        },
        "city" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "email" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "employer" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "firstname" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "gender" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "lastname" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "state" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        }
      }
    }
  }
}

文档操作

  • 在索引中添加文档;
json
PUT /customer/doc/1
{
  "name": "John Doe"
}
json
{
  "_index" : "customer",
  "_type" : "doc",
  "_id" : "1",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 0,
  "_primary_term" : 1
}
  • 查看索引中的文档;
json
GET /customer/doc/1
json
{
  "_index" : "customer",
  "_type" : "doc",
  "_id" : "1",
  "_version" : 1,
  "_seq_no" : 0,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "name" : "John Doe"
  }
}
  • 修改索引中的文档:
json
POST /customer/doc/1/_update
{
  "doc": { "name": "Jane Doe" }
}
json
{
  "_index": "customer",
  "_type": "doc",
  "_id": "1",
  "_version": 2,
  "result": "updated",
  "_shards": {
    "total": 2,
    "successful": 1,
    "failed": 0
  },
  "_seq_no": 4,
  "_primary_term": 1
}
  • 删除索引中的文档;
json
DELETE /customer/doc/1
json
{
  "_index" : "customer",
  "_type" : "doc",
  "_id" : "1",
  "_version" : 2,
  "result" : "deleted",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 1,
  "_primary_term" : 1
}
  • 对索引中的文档执行批量操作;
json
POST /customer/doc/_bulk
{"index":{"_id":"1"}}
{"name": "John Doe" }
{"index":{"_id":"2"}}
{"name": "Jane Doe" }
json
{
  "took" : 9,
  "errors" : false,
  "items" : [
    {
      "index" : {
        "_index" : "customer",
        "_type" : "doc",
        "_id" : "1",
        "_version" : 3,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 2,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "index" : {
        "_index" : "customer",
        "_type" : "doc",
        "_id" : "2",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 3,
        "_primary_term" : 1,
        "status" : 201
      }
    }
  ]
}

数据搜索

查询表达式(Query DSL)是一种非常灵活又富有表现力的查询语言,Elasticsearch使用它可以以简单的JSON接口来实现丰富的搜索功能,下面的搜索操作都将使用它。

数据导入

  • 首先我们需要导入一定量的数据用于搜索,使用的是银行账户表的例子,数据结构如下:
json
{
    "account_number": 0,
    "balance": 16623,
    "firstname": "Bradshaw",
    "lastname": "Mckenzie",
    "age": 29,
    "gender": "F",
    "address": "244 Columbus Place",
    "employer": "Euron",
    "email": "bradshawmckenzie@euron.com",
    "city": "Hobucken",
    "state": "CO"
}
json
POST /bank/account/_bulk
{
  "index": {
    "_id": "1"
  }
}
{
  "account_number": 1,
  "balance": 39225,
  "firstname": "Amber",
  "lastname": "Duke",
  "age": 32,
  "gender": "M",
  "address": "880 Holmes Lane",
  "employer": "Pyrami",
  "email": "amberduke@pyrami.com",
  "city": "Brogan",
  "state": "IL"
}
......省略若干条数据
  • 导入完成后查看索引信息,可以发现bank索引中已经创建了1000条文档。
json
GET /_cat/indices?v
health status index                           uuid                   pri rep docs.count docs.deleted store.size pri.store.size
yellow open   bank                            ycOSgiWjQomwzdygGwqOrQ   1   1       1000            0    374.5kb        374.5kb

搜索入门

  • 最简单的搜索,使用match_all来表示,例如搜索全部;
json
GET /bank/_search
{
  "query": { "match_all": {} }
}

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  • 分页搜索,from表示偏移量,从0开始,size表示每页显示的数量;
json
GET /bank/_search
{
  "query": { "match_all": {} },
  "from": 0,
  "size": 10
}

image.png

  • 搜索排序,使用sort表示,例如按balance字段降序排列;
json
GET /bank/_search
{
  "query": { "match_all": {} },
  "sort": { "balance": { "order": "desc" } }
}

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  • 搜索并返回指定字段内容,使用_source表示,例如只返回account_number和balance两个字段内容:
json
GET /bank/_search
{
  "query": { "match_all": {} },
  "_source": ["account_number", "balance"]
}

image.png

条件搜索

  • 条件搜索,使用match表示匹配条件,例如搜索出account_number为20的文档:
json
GET /bank/_search
{
  "query": {
    "match": {
      "account_number": 20
    }
  }
}

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  • 文本类型字段的条件搜索,例如搜索address字段中包含mill的文档,对比上一条搜索可以发现,对于数值类型match操作使用的是精确匹配,对于文本类型使用的是模糊匹配;
json
GET /bank/_search
{
  "query": {
    "match": {
      "address": "mill"
    }
  },
  "_source": [
    "address",
    "account_number"
  ]
}

image.png

  • 短语匹配搜索,使用match_phrase表示,例如搜索address字段中同时包含mill和lane的文档:
json
GET /bank/_search
{
  "query": {
    "match_phrase": {
      "address": "mill lane"
    }
  }
}

image.png

组合搜索

  • 组合搜索,使用bool来进行组合,must表示同时满足,例如搜索address字段中同时包含mill和lane的文档;
json
GET /bank/_search
{
  "query": {
    "bool": {
      "must": [
        { "match": { "address": "mill" } },
        { "match": { "address": "lane" } }
      ]
    }
  }
}

image.png

  • 组合搜索,should表示满足其中任意一个,搜索address字段中包含mill或者lane的文档;
json
GET /bank/_search
{
  "query": {
    "bool": {
      "should": [
        { "match": { "address": "mill" } },
        { "match": { "address": "lane" } }
      ]
    }
  }
}

image.png

  • 组合搜索,must_not表示同时不满足,例如搜索address字段中不包含mill且不包含lane的文档;
json
GET /bank/_search
{
  "query": {
    "bool": {
      "must_not": [
        { "match": { "address": "mill" } },
        { "match": { "address": "lane" } }
      ]
    }
  }
}

image.png

  • 组合搜索,组合must和must_not,例如搜索age字段等于40且state字段不包含ID的文档;
json
GET /bank/_search
{
  "query": {
    "bool": {
      "must": [
        { "match": { "age": "40" } }
      ],
      "must_not": [
        { "match": { "state": "ID" } }
      ]
    }
  }
}

image.png

过滤搜索

  • 搜索过滤,使用filter来表示,例如过滤出balance字段在20000~30000的文档;
json
GET /bank/_search
{
  "query": {
    "bool": {
      "must": { "match_all": {} },
      "filter": {
        "range": {
          "balance": {
            "gte": 20000,
            "lte": 30000
          }
        }
      }
    }
  }
}

image.png

搜索聚合

  • 对搜索结果进行聚合,使用aggs来表示,类似于MySql中的group by,例如对state字段进行聚合,统计出相同state的文档数量;
json
GET /bank/_search
{
  "size": 0,
  "aggs": {
    "group_by_state": {
      "terms": {
        "field": "state.keyword"
      }
    }
  }
}

image.png

  • 嵌套聚合,例如对state字段进行聚合,统计出相同state的文档数量,再统计出balance的平均值;
json
GET /bank/_search
{
  "size": 0,
  "aggs": {
    "group_by_state": {
      "terms": {
        "field": "state.keyword"
      },
      "aggs": {
        "average_balance": {
          "avg": {
            "field": "balance"
          }
        }
      }
    }
  }
}

image.png

  • 对聚合搜索的结果进行排序,例如按balance的平均值降序排列;
json
GET /bank/_search
{
  "size": 0,
  "aggs": {
    "group_by_state": {
      "terms": {
        "field": "state.keyword",
        "order": {
          "average_balance": "desc"
        }
      },
      "aggs": {
        "average_balance": {
          "avg": {
            "field": "balance"
          }
        }
      }
    }
  }
}

image.png

  • 按字段值的范围进行分段聚合,例如分段范围为age字段的[20,30] [30,40] [40,50],之后按gender统计文档个数和balance的平均值;
json
GET /bank/_search
{
  "size": 0,
  "aggs": {
    "group_by_age": {
      "range": {
        "field": "age",
        "ranges": [
          {
            "from": 20,
            "to": 30
          },
          {
            "from": 30,
            "to": 40
          },
          {
            "from": 40,
            "to": 50
          }
        ]
      },
      "aggs": {
        "group_by_gender": {
          "terms": {
            "field": "gender.keyword"
          },
          "aggs": {
            "average_balance": {
              "avg": {
                "field": "balance"
              }
            }
          }
        }
      }
    }
  }
}

image.png

参考资料

https://www.elastic.co/guide/en/elasticsearch/reference/7.17/getting-started.html