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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
- 下载Elasticsearch7.17.3版本的zip包,并解压到指定目录,下载地址:https://www.elastic.co/cn/downloads/past-releases/elasticsearch-7-17-3

- 安装中文分词器,注意下载与Elasticsearch对应的版本,下载地址:https://github.com/medcl/elasticsearch-analysis-ik/releases

- 下载完成后解压到Elasticsearch的plugins目录下;

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

- 如果遇到双击elasticsearch.bat闪退的情况,可以下载一个解压版的JDK 11并进行解压,下载地址:https://mirrors.tuna.tsinghua.edu.cn/Adoptium/11/jdk/x64/windows/

- 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。

Kibana
- 下载Kibana,作为访问Elasticsearch的客户端,请下载7.17.3版本的zip包,并解压到指定目录,下载地址:https://www.elastic.co/cn/downloads/past-releases/kibana-7-17-3

- 运行bin目录下的kibana.bat,启动Kibana服务;

- 打开Kibana的用户界面,访问地址:http://localhost:5601

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/- 安装中文分词器IKAnalyzer,注意下载与Elasticsearch对应的版本,下载地址:https://github.com/medcl/elasticsearch-analysis-ik/releases

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

- 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- 访问会返回版本信息:http://192.168.3.101:9200
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- 访问地址进行测试:http://192.168.3.101:5601

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;

- 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;

- 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?vip 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?vhealth 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?vhealth 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?vhealth 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/_mappingjson
{
"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/1json
{
"_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/1json
{
"_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"
}- 我们先复制下需要导入的数据,数据地址:https://github.com/macrozheng/mall-learning/blob/teach/document/json/accounts.json
- 然后直接使用批量操作来导入数据,注意本文所有操作都在Kibana的Dev Tools中进行;
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?vhealth 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": {} }
}
- 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
}
- 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" } }
}
- 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"]
}
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
}
}
}
- 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"
]
}
- 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"
}
}
}
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" } }
]
}
}
}
- 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" } }
]
}
}
}
- 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" } }
]
}
}
}
- 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" } }
]
}
}
}
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
}
}
}
}
}
}
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"
}
}
}
}
- 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"
}
}
}
}
}
}
- 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"
}
}
}
}
}
}
- 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"
}
}
}
}
}
}
}
}
参考资料
https://www.elastic.co/guide/en/elasticsearch/reference/7.17/getting-started.html