Elasticsearch简单入门

环境

  • centos 8 1C2G
  • jdk8

安装

一开始下载tar.gz然后手动起的,一执行报个错说不能用root用户启动,索性直接用rpm安装,帮你把所有事情做好,包括设置systemd服务,这样很爽

wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.6.2.rpm
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.6.2.rpm.sha512
shasum -a 512 -c elasticsearch-6.6.2.rpm.sha512 
sudo rpm --install elasticsearch-6.6.2.rpm

贴一下官方文档:https://www.elastic.co/guide/en/elasticsearch/reference/6.6/rpm.html

使用rpm安装后的es相关文件布局如下:

Type Description Default Location Setting
home Elasticsearch home directory or $ES_HOME /usr/share/elasticsearch
bin Binary scripts including elasticsearch to start a node and elasticsearch-plugin to install plugins /usr/share/elasticsearch/bin
conf Configuration files including elasticsearch.yml /etc/elasticsearch ES_PATH_CONF
conf Environment variables including heap size, file descriptors. /etc/sysconfig/elasticsearch
data The location of the data files of each index / shard allocated on the node. Can hold multiple locations. /var/lib/elasticsearch path.data
logs Log files location. /var/log/elasticsearch path.logs
plugins Plugin files location. Each plugin will be contained in a subdirectory. /usr/share/elasticsearch/plugins
repo Shared file system repository locations. Can hold multiple locations. A file system repository can be placed in to any subdirectory of any directory specified here. Not configured path.repo

配置

# 监听所有网卡
sed -i "s/network.host:.*/network.host: 0.0.0.0/g" /etc/elasticsearch/elasticsearch.yml
# 修改名字
sed -i "s/node.name:.*/node.name: TEST/g" /etc/elasticsearch/elasticsearch.yml
# 重启服务
service elasticsearch restart

先不设置密码认证了,大胆用

Elasticsearch-Head使用

这是一个可视化监控es的web工具

直接使用chrome扩展:https://chrome.google.com/webstore/detail/elasticsearch-head/ffmkiejjmecolpfloofpjologoblkegm/

官方文档

https://esdoc.arloor.com/guide/en/elasticsearch/reference/6.6/index.html

https://www.elastic.co/guide/en/elasticsearch/reference/6.6/index.html

简单操作

新建索引

以下操作在elasticsearch-head操作

put /users

{
  "settings": {
    "number_of_shards": 1,
    "number_of_replicas": 0
  },
  "mappings": {
    "user": {
      "properties": {
        "name": {
          "type": "text"
        }
      }
    }
  }
}
  • index_name只能是小写,且不能出现一些特殊字符
  • number_of_replicas副本数量在这里设置成0.因为是单节点的es,设置大于0的副本数不起作用,且在head中会看到unassigned

增加document

PUT users/user/1
{
  "name":"刘港欢"
}

ES领域特定查询语言

  • json格式
  • 可以看做是一个抽象语法树,包含两种query语句
    • 叶query语句——查询特定field的指定value{match、term、range}
    • 组合query语句。wrap other leaf or compound queries。

查询语句在query上下文和filter上下文中的表现不同

query上下文

回答“该文档与查询有多相关”(how much)的问题

当查询语句被传递给“query”参数时生效

会计算相关度打分_score

filter上下文

回答”是不是与该查询相关”(is or no)的问题,用于过滤。

为了提高性能,ES把常用的filters自动缓存。

In effect whenever a query clause is passed to a filter parameter,

  1. filter or must_not parameters in the bool query,
  2. the filter parameter in the constant_score query
  3. the filter aggregation.
{
  "query": { //query上下文
    "bool": { //bool查询下可以有must/should/filter/must_not
      "must": [
        { "match": { "title":   "Search"        }}, 
        { "match": { "content": "Elasticsearch" }}  
      ],
      "filter": [ //filter上下文
        { "term":  { "status": "published" }}, 
        { "range": { "publish_date": { "gte": "2015-01-01" }}} 
      ]
    }
  }
}

三种查询方式

http://<server>/_search
查询所有index、type
http://<server>/<index_name(s)>/_search
查询多个index,逗号分隔
http://<server>/<index_name(s)>/<type_name(s)>/_search
查询多个index,多个type,逗号分隔

index_name可以使用别名

match_all查询

返回所有的文档

curl -X GET "localhost:9200/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "query": {
        "match_all": {}
    }
}
'

full text queries

  1. match
  2. match_phrase
  3. match_phrase_prefix
  4. multi_match
  5. common
  6. query_string

Term Lavel Queries

term-level-queries.html