[C++][第三方库][Elasticsearch]详细讲授
1.介绍[*]Elasticsearch，简称ES，它是个开源分布式搜刮引擎
[*]特点：分布式，零配置，主动发现，索引主动分片，索引副本机制，restful风格接口，多数据源，主动搜刮负载等
[*]它可以近乎及时的存储、检索数据；本身扩展性很好，可以扩展到上百台服务器，处理PB级别的数据
[*]ES也利用Java开发并利用Lucene作为其核心来实现所有索引和搜刮的功能，但是它的目标是通过简单的RESTfulAPI来隐蔽Lucene的复杂性，从而让全文搜刮变得简单
[*]Elasticsearch是**面向文档**(document oriented)的
[*]这意味着它可以存储整个对象或文档(document)
[*]然而它不仅仅是存储，还会索引(index)每个文档的内容使之可以被搜刮
[*]可以对文档(而非成行成列的数据)举行索引、搜刮、排序、过滤
2.安装
1.ES
[*]添加堆栈密钥：上边的添加方式会导致一个apt-key的警告，假如不想报警告利用下边这个# 1.
wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -
# 2.
curl -s https://artifacts.elastic.co/GPG-KEY-elasticsearch | \
sudo gpg --no-default-keyring \
--keyring gnupg-ring:/etc/apt/trusted.gpg.d/icsearch.gpg --import
[*]添加镜像源堆栈：echo "deb https://artifacts.elastic.co/packages/7.x/apt stable main" \
| sudo tee /etc/apt/sources.list.d/elasticsearch.list
[*]更新软件包列表：sudo apt update
[*]安装ES：sudo apt-get install elasticsearch=7.17.21
[*]启动ES：sudo systemctl start elasticsearch
[*]安装ik分词器插件：sudo /usr/share/elasticsearch/bin/elasticsearch-plugin install \
https://get.infini.cloud/elasticsearch/analysis-ik/7.17.21
[*]检察ES服务的状态：sudo systemctl status elasticsearch.service
[*]验证ES是否安装乐成：curl -X GET "http://localhost:9200/"
[*]设置外网访问：默认只能在本机举行访问，修改后欣赏器访问IP:PORTvim /etc/elasticsearch/elasticsearch.yml
# 新增配置
network.host: 0.0.0.0
http.port: 9200
cluster.initial_master_nodes: ["node-1"]
[*]假如启动ES的时间出现报错：
[*]解决方法：# 调整ES虚拟内存，虚拟内存默认最大映射数为65530，无法满足ES系统要求， 需要调整为262144以上
sudo sysctl -w vm.max_map_count=262144
# 增加虚拟机内存配置
sudo vim /etc/elasticsearch/jvm.options
# 新增如下内容
-Xms512m
-Xmx512m
Job for elasticsearch.service failed because the control process exited with error code.
See "systemctl status elasticsearch.service" and "journalctl -xeu elasticsearch.service" for details.
2.Kibana
[*]安装Kibana：sudo apt install kibana
[*]配置Kibana(可选)：根据须要配置Kibana，配置文件通常位于/etc/kibana/kibana.yml，可能须要设置如服务器地址、端口、Elasticsearch URL等
[*]启动Kibana：sudo systemctl start kibana
[*]设置开机自启(可选)：sudo systemctl enable kibana
[*]访问Kibana：http://<ip>:5601
3.ES核心概念
1.索引(index)
[*]一个索引就是一个拥有几分相似特性的文档的聚集
[*]比方：
[*]有一个客户数据的索引，一个产物目次的索引，另有一个订单数据的索引
[*]一个索引由一个名字来标识(必须全部是小写字母的)，并且当要对应于这个索引中的文档举行索引、搜刮、更新和删除的时间，都要利用到这个名字
[*]在一个集群中，可以定义任意多的索引
[*]索引类似于数据库中库的概念
[*]数据库中的库，表示了一组数据的聚集
[*]ES中的索引，是一组相似特性数据的聚集
2.类型(Type)
[*]在一个索引中，可以定义一种或多种类型
[*]一个类型是索引的一个逻辑上的分类/分区，其语义完全由用户来定
[*]通常，会为具有一组共同字段的文档定义一个类型
[*]比方：
[*]运营一个博客平台并且将所有的数据存储到一个索引中
[*]在这个索引中，可以为用户数据定义一个类型，为博客数据定义另一个类型，为评论数据定义另一个类型
[*][类型]类似于数据库中表的概念，在索引的概念下，又对数据聚集举行了一层细分
[*]现在[类型]几乎已经弃用
3.字段(Field)
[*]字段相当于是数据库表的字段，对文档数据根据不同属性举行的分类标识 -> 数据类型
![]
4.映射(mapping)
[*]映射是在处理数据的方式和规则方面做一些限定
[*]某个字段的数据类型、默认值、分析器、是否被索引等等，这些都是映射里面可以设置的
[*]映射类似于告诉ES哪些字段须要分词，做出索引映射，可以大概举行数据检索
[*]别的就是处理ES里面数据的一些利用规则设置也叫做映射
[*]按着最优规则处理数据对性能进步很大，因此才须要建立映射，并且须要思考如何建立映射才能对性能更好
[*]详细规则：
[*]enabled：是否仅作存储，不做搜刮和分析
[*]取值：true(默认)/false
[*]index：是否构建倒排索引(决定了是否分词，是否被索引)
[*]取值：true(默认)/false
[*]index_option
[*]dynamic：控制mapping的主动更新
[*]取值：true(默认)/false
[*]doc_value：是否开启doc_value，用户聚合和排序分析，分词字段不能利用
[*]取值：true(默认)/false
[*]fielddata：是否为text类型启动fielddata，实现排序和聚合分析
[*]针对分词字段，参与排序或聚合时能进步性能
[*]不分词字段统一发起利用doc_valuefielddata": {
"format": "disabled"
}
[*]store：是否单独设置此字段的是否存储而从_source字段中分离
[*]取值：true/false(默认)
[*]coerce：是否开启主动数据类型转换功能，如字符串转整形，浮点转整形
[*]取值：true(默认)/false
[*]analyzer：指定分词器，默认分词器是standard analyzer
[*]示例：”analyzer”: “ik”
[*]boost：字段级别的分数加权，默认值是1.0
[*]示例：”boost”: 1.25
[*]fields：对一个字段提供多种索引模式，同一个字段的值，一个分词一个不分词"fields": {
"raw": {
"type": "text",
"index": "not_analyzed"
}
}
[*]data_detection：是否主动识别日期类型
[*]取值：true(默认)/false
5.文档(document)
[*] 一个文档是一个可被索引的基础信息单元
[*] 比方：某一个客户的文档，某一个产物的一个文档大概某个订单的一个文档
[*]文档以JSON格式来表示，而JSON是一个到处存在的互联网数据交互格式
[*]在一个index/type里面，可以存储任意多的文档
[*]一个文档必须被索引大概赋予一个索引的type
[*] Elasticsearch与传统关系性数据库相比：
DBDatabaseTableRowColumnESIndexTypeDocumentField
4.Kibana访问ES举行测试
[*]创建索引库：POST /user/_doc
{
"settings" : {
"analysis" : {
"analyzer" : {
"ik" : {
"tokenizer" : "ik_max_word"
}
}
}
},
"mappings" : {
"dynamic" : true,
"properties" : {
"nickname" : {
"type" : "text",
"analyzer" : "ik_max_word"
},
"user_id" : {
"type" : "keyword",
"analyzer" : "standard"
},
"phone" : {
"type" : "keyword",
"analyzer" : "standard"
},
"description" : {
"type" : "text",
"enabled" : false
},
"avatar_id" : {
"type" : "keyword",
"enabled" : false
}
}
}
}
[*]新增数据：
[*]插入形式：POST /user/_doc/_bulk
{"index":{"_id":"1"}}
{"user_id" : "USER4b862aaa-2df8654a-7eb4bb65e3507f66","nickname" : "昵称1","phone" : "手机号1","description" : "签名1","avatar_id" : "头像1"}
{"index":{"_id":"2"}}
{"user_id" : "USER14eeeaa5-442771b9-0262e455e4663d1d","nickname" : "昵称2","phone" : "手机号2","description" : "签名2","avatar_id" : "头像2"}
{"index":{"_id":"3"}}
{"user_id" : "USER484a6734-03a124f0-996c169dd05c1869","nickname" : "昵称3","phone" : "手机号3","description" : "签名3","avatar_id" : "头像3"}
{"index":{"_id":"4"}}
{"user_id" : "USER186ade83-4460d4a6-8c08068f83127b5d","nickname" : "昵称4","phone" : "手机号4","description" : "签名4","avatar_id" : "头像4"}
{"index":{"_id":"5"}}
{"user_id" : "USER6f19d074-c33891cf-23bf5a8357189a19","nickname" : "昵称5","phone" : "手机号5","description" : "签名5","avatar_id" : "头像5"}
{"index":{"_id":"6"}}
{"user_id" : "USER97605c64-9833ebb7-d045535335a59195","nickname" : "昵称6","phone" : "手机号6","description" : "签名6","avatar_id" : "头像6"}
[*]便于阅读：[
{
"index": {
"_id": "1"
},
"user": {
"user_id": "USER4b862aaa-2df8654a-7eb4bb65e3507f66",
"nickname": "昵称1",
"phone": "手机号1",
"description": "签名1",
"avatar_id": "头像1"
}
},
{
"index": {
"_id": "2"
},
"user": {
"user_id": "USER14eeeaa5-442771b9-0262e455e4663d1d",
"nickname": "昵称2",
"phone": "手机号2",
"description": "签名2",
"avatar_id": "头像2"
}
},
{
"index": {
"_id": "3"
},
"user": {
"user_id": "USER484a6734-03a124f0-996c169dd05c1869",
"nickname": "昵称3",
"phone": "手机号3",
"description": "签名3",
"avatar_id": "头像3"
}
},
{
"index": {
"_id": "4"
},
"user": {
"user_id": "USER186ade83-4460d4a6-8c08068f83127b5d",
"nickname": "昵称4",
"phone": "手机号4",
"description": "签名4",
"avatar_id": "头像4"
}
},
{
"index": {
"_id": "5"
},
"user": {
"user_id": "USER6f19d074-c33891cf-23bf5a8357189a19",
"nickname": "昵称5",
"phone": "手机号5",
"description": "签名5",
"avatar_id": "头像5"
}
},
{
"index": {
"_id": "6"
},
"user": {
"user_id": "USER97605c64-9833ebb7-d045535335a59195",
"nickname": "昵称6",
"phone": "手机号6",
"description": "签名6",
"avatar_id": "头像6"
}
}
]
[*]检察并搜刮数据:GET /user/_doc/_search?pretty
{
"query" : {
"bool" : {
"must_not" : [
{
"terms" : {
"user_id.keyword" : [
"USER4b862aaa-2df8654a-7eb4bb65e3507f66",
"USER14eeeaa5-442771b9-0262e455e4663d1d",
"USER484a6734-03a124f0-996c169dd05c1869"
]
}
}
],
"should" : [
{
"match" : {
"user_id" : "昵称"
}
},
{
"match" : {
"nickname" : "昵称"
}
},
{
"match" : {
"phone" : "昵称"
}
}
]
}
}
}
[*]删除索引：DELETE /user
[*]查询所有数据：POST /user/_doc/_search
{
"query":
{
"match_all":{}
}
}
5.ES客户端的安装
[*]代码
[*]官网
[*]ES C++的客户端选择并不多， 这里利用elasticlient库
[*]前置安装：依靠MicroHTTPD库sudo apt-get install libmicrohttpd-dev
[*]安装：# 克隆代码
git clone https://github.com/seznam/elasticlient
# 切换目录
cd elasticlient
# 更新子模块
git submodule update --init --recursive
# 编译代码
make build && cd build
cmake ..
make
# 安装
make install
6.ES客户端接口介绍
/**
* Perform search on nodes until it is successful. Throws
exception if all nodes
* has failed to respond.
* \param indexName specification of an Elasticsearch index.
* \param docType specification of an Elasticsearch document type.
* \param body Elasticsearch request body.
* \param routing Elasticsearch routing. If empty, no routing has
been used.
*
* \return cpr::Response if any of node responds to request.
* \throws ConnectionException if all hosts in cluster failed to
respond.
*/
cpr::Response search(const std::string &indexName,
const std::string &docType,
const std::string &body,
const std::string &routing = std::string());
/**
* Get document with specified id from cluster. Throws exception
if all nodes
* has failed to respond.
* \param indexName specification of an Elasticsearch index.
* \param docType specification of an Elasticsearch document type.
* \param id Id of document which should be retrieved.
* \param routing Elasticsearch routing. If empty, no routing has
been used.
*
* \return cpr::Response if any of node responds to request.
* \throws ConnectionException if all hosts in cluster failed to
respond.
*/
cpr::Response get(const std::string &indexName,
const std::string &docType,
const std::string &id = std::string(),
const std::string &routing = std::string());
/**
* Index new document to cluster. Throws exception if all nodes
has failed to respond.
* \param indexName specification of an Elasticsearch index.
* \param docType specification of an Elasticsearch document type.
* \param body Elasticsearch request body.
* \param id Id of document which should be indexed. If empty, id
will be generated
* automatically by Elasticsearch cluster.
* \param routing Elasticsearch routing. If empty, no routing has
been used.
*
* \return cpr::Response if any of node responds to request.
* \throws ConnectionException if all hosts in cluster failed to
respond.
*/
cpr::Response index(const std::string &indexName,
const std::string &docType,
const std::string &id,
const std::string &body,
const std::string &routing = std::string());
/**
* Delete document with specified id from cluster. Throws
exception if all nodes
* has failed to respond.
* \param indexName specification of an Elasticsearch index.
* \param docType specification of an Elasticsearch document type.
* \param id Id of document which should be deleted.
* \param routing Elasticsearch routing. If empty, no routing has
been used.
*
* \return cpr::Response if any of node responds to request.
* \throws ConnectionException if all hosts in cluster failed to
respond.
*/
cpr::Response remove(const std::string &indexName,
const std::string &docType,
const std::string &id,
const std::string &routing = std::string());
7.利用
[*]ES客户端利用注意：
[*]地址后边不要忘了相对根目次：http://127.0.0.1:9200/
[*]ES客户端API利用时，要举行异常捕捉，否则操纵失败会导致程序异常退出
#include <iostream>
#include <elasticlient/client.h>
#include <cpr/cpr.h>
int main()
{
// 1.构造ES客户端
elasticlient::Client client({"http://127.0.0.1:9200/"});
// 2.发起搜索请求
try
{
auto resp = client.search("user", "_doc",
"{\"query\": { \"match_all\":{} }}");
std::cout << resp.status_code << std::endl;
std::cout << resp.text << std::endl;
}
catch(std::exception &e)
{
std::cout << e.what() << std::endl;
return -1;
}
return 0;
}
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