Elasticsearch学习笔记

这篇博客用于记录学习和使用Elasticsearch的过程，主要内容包括安装配置和通过Python访问Elasticsearch。Tips: Elasticsearch安装在一台Linux服务器上。

Elasticsearch学习笔记

安装配置Elasticsearch

下载安装包：Download Elasticsearch;
解压缩：tar -xvf elasticsearch-7.15.2-linux-x86_64.tar.gz;
修改config目录下的elasticsearch.yml文件，配置局域网访问：network.host: 0.0.0.0;

切换到bin目录，敲击命令./elasticsearch启动Elasticsearch，出现以下错误信息：

ERROR: [2] bootstrap checks Failed. You must address the points described in the following [2] lines before starting Elasticsearch.
bootstrap check failure [1] of [2]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
bootstrap check failure [2] of [2]: the default discovery settings are unsuitable for production use; at least one of [discovery.seed_hosts, discovery.seed_providers, cluster.initial_master_nodes] must be configured

由于当前用户拥有的内存权限太小，Elasticsearch不能正常启动，需要修改系统配置文件/etc/sysctl.conf，设置vm.max_map_count=262144，重启系统（或执行sysctl -w vm.max_map_count=262144）;
另外，由于没有指定以下配置项，Elasticsearch不能正常启动：
- discovery.seed_hosts: 集群主机列表；
- discovery.seed_providers: 基于配置文件配置集群主机列表；
- cluster.initial_master_nodes: 启动时初始化的参与选主的node，生产环境必填。
修改配置文件elasticsearch.yml，设置discovery.seed_hosts: ["192.168.1.xx"]和cluster.initial_master_nodes: ["192.168.1.xx:9300"];

重新启动Elasticsearch，浏览器访问http://192.168.1.xx:9200/：

{
"name" : "xxxx",
"cluster_name" : "elasticsearch",
"cluster_uuid" : "4urQVMKyQgGl0oTM_wvgjQ",
"version" : {
	"number" : "7.15.2",
	"build_flavor" : "default",
	"build_type" : "tar",
	"build_hash" : "93d5a7f6192e8a1a12e154a2b81bf6fa7309da0c",
	"build_date" : "2021-11-04T14:04:42.515624022Z",
	"build_snapshot" : false,
	"lucene_version" : "8.9.0",
	"minimum_wire_compatibility_version" : "6.8.0",
	"minimum_index_compatibility_version" : "6.0.0-beta1"
},
"tagline" : "You KNow, for Search"
}

安装、配置成功！

通过Python访问Elasticsearch

安装Elasticsearch的Python客户端：conda install elasticsearch;

连接Elasticsearch:

from elasticsearch import Elasticsearch

es = Elasticsearch(hosts=['192.168.1.xx'])
result = es.indices.create(index='news_and_events', ignore=400)  # 状态码400表示由于已经存在同名Index，创建失败
print(result)

安装插件elasticsearch-analysis-ik，使Elasticsearch具备中文分词的能力：

./elasticsearch-plugin install https://github.com/medcl/elasticsearch-analysis-ik/releases/download/v7.15.2/elasticsearch-analysis-ik-7.15.2.zip

安装成功后，重启Elasticsearch；

填充数据：

from elasticsearch import Elasticsearch
from tqdm import tqdm

# 导入本地的模块
from database import SessionLocal
from models import Record

es = Elasticsearch(hosts=['192.168.1.xx'])
mapping = {
	'properties': {
		'title': {
			'type': 'text',
			'analyzer': 'ik_max_word',
			'search_analyzer': 'ik_max_word'
		},
		'content': {
			'type': 'text',
			'analyzer': 'ik_max_word',
			'search_analyzer': 'ik_max_word'
		}
	}
}
es.indices.create(index='news_and_events', ignore=400)  # Elasticsearch中的index可以类比关系型数据库里面的database
es.indices.put_mapping(index='news_and_events', doc_type='records', body=mapping, include_type_name=True)  # doc_type类比关系模式

# 查询数据库，导出所有的新闻和公告
db = SessionLocal()
result_set = db.query(Record).all()

for record in tqdm(result_set):
	data = {
		'record_id': record.record_id,
		'title': record.title,
		'content': record.content
	}
	es.create(index='news_and_events', doc_type='records', id=record.record_id, document=data)

# 关闭数据库和Elasticsearch连接
db.close()
es.close()

查询数据：

q = {
		'query': {
			'multi_match': {
				'query': '成都重庆双城经济圈',
				'fields': ['title^2', 'content']
			}
		}
	}
results = es.search(q, index='news_and_events', doc_type='records')

Elasticsearch返回的结果：

{
	"took": 10,
	"timed_out": false,
	"_shards": {
		"total": 1,
		"successful": 1,
		"skipped": 0,
		"Failed": 0
	},
	"hits": {
		"total": {
			"value": 623,
			"relation": "eq"
		},
		"max_score": 57.087215,
		"hits": [
			{
				"_index": "news_and_events",
				"_type": "records",
				"_id": "2508",
				"_score": 57.087215,
				"_source": {
					"record_id": 2508,
					"title": "关于成渝地区双城经济圈创新创业峰会的通知",
					"content": "各学院，各位老师和同学：\n现转发重庆市教育委员会和四川省教育厅等六部门联合发布的《关于举办\"智创巴蜀\"首届成渝地区双城经济圈创新创业峰会的通知》，详见附件。欢迎积极参加。\n联系人：x老师\n联系电话：xxxxxxxx\n教务处\nxxxx年xx月xx日\n附件1-川渝6部门联合发峰会正式文件"
				}
			}
		]
	}
}

Elasticsearch学习笔记

Elasticsearch学习笔记

安装配置Elasticsearch

通过Python访问Elasticsearch

参考资料：

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