ElasticSearch基础篇-安装与基本操作

ElasticSearch基础篇

安装

官网

下载地址

下载完成后对文件进行解压，项目结构如下

• 进入bin目录点击elasticsearch.bat启动服务

• 9300 端口为 Elasticsearch 集群间组件的通信端口， 9200 端口为浏览器访问的 http协议 RESTful 端口

• 打开浏览器，输入地址： http://localhost:9200，返回结果如下

  {
    "name" : "暗影精灵8",
    "cluster_name" : "elasticsearch",
    "cluster_uuid" : "9oaD9__3R_6WxskWlWe4iA",
    "version" : {
      "number" : "7.8.0",
      "build_flavor" : "default",
      "build_type" : "zip",
      "build_hash" : "757314695644ea9a1dc2fecd26d1a43856725e65",
      "build_date" : "2020-06-14T19:35:50.234439Z",
      "build_snapshot" : false,
      "lucene_version" : "8.5.1",
      "minimum_wire_compatibility_version" : "6.8.0",
      "minimum_index_compatibility_version" : "6.0.0-beta1"
    },
    "tagline" : "You Know, for Search"
  }
  

倒排索引

什么是倒排索引?

倒排索引（英语：Inverted index），也常被称为反向索引、置入档案或反向档案，是一种索引方法，被用来存储在全文搜索下某个单词在一个文档或者一组文档中的存储位置的映射。它是文档检索系统中最常用的数据结构。通过倒排索引，可以根据单词快速获取包含这个单词的文档列表。倒排索引主要由两个部分组成：“单词词典”和“倒排文件”

正排索引

id	content
1001	my name is zhang san
1002	my name is li si

• 对id创建索引，通过id查询对应的内容，如果通过id查询匹配关键字效率极低

倒排索引

keyword	id
name	1001,1002
zhang	1001

• 根据关键字查询对应的id

简单理解:正排索引是根据存储位置获取对应的内容，倒排索引是通过对应的内容获取存储位置

MySQL与ES结构关系

ES 里的 Index 可以看做一个库，而 Types 相当于表， Documents 则相当于表的行。这里 Types 的概念已经被逐渐弱化， Elasticsearch 6.X 中，一个 index 下已经只能包含一个type， Elasticsearch 7.X 中, Type 的概念已经被删除了

基本操作

创建索引

PUT http://localhost:9200/index_name

创建成功

{
    "acknowledged": true,
    "shards_acknowledged": true,
    "index": "shopping"
}

创建失败:索引已存在

{
    "error": {
        "root_cause": [
            {
                "type": "resource_already_exists_exception",
                "reason": "index [shopping/8ra6Z1w3RiudhIMMlYkkNw] already exists",
                "index_uuid": "8ra6Z1w3RiudhIMMlYkkNw",
                "index": "shopping"
            }
        ],
        "type": "resource_already_exists_exception",
        "reason": "index [shopping/8ra6Z1w3RiudhIMMlYkkNw] already exists",
        "index_uuid": "8ra6Z1w3RiudhIMMlYkkNw",
        "index": "shopping"
    },
    "status": 400
}

查询索引

GET http://localhost:9200/shopping

响应结果

{
    "shopping": {
        "aliases": {},
        "mappings": {},
        "settings": {
            "index": {
                "creation_date": "1690355410054",
                "number_of_shards": "1",
                "number_of_replicas": "1",
                "uuid": "8ra6Z1w3RiudhIMMlYkkNw",
                "version": {
                    "created": "7080099"
                },
                "provided_name": "shopping"
            }
        }
    }
}

查询所有索引

GET http://localhost:9200/_cat/indices?v

响应结果

health status index    uuid                   pri rep docs.count docs.deleted store.size pri.store.size
yellow open   shopping 8ra6Z1w3RiudhIMMlYkkNw   1   1          0            0       208b           208b

删除索引

DELETE http://localhost:9200/shopping

响应结果

{
    "acknowledged": true
}

创建文档

POST http://127.0.0.1:9200/shopping/_doc

body type:json

{
    "title":"小米手机",
    "category":"小米",
    "images":"http://www.gulixueyuan.com/xm.jpg",
    "price":3999.00
}

响应结果

{
    "_index": "shopping",
    "_type": "_doc",
    "_id": "44MZkYkBpGe0S7oK7CQ2",
    "_version": 1,
    "result": "created",
    "_shards": {
        "total": 2,
        "successful": 1,
        "failed": 0
    },
    "_seq_no": 0,
    "_primary_term": 1
}

• _id:每次创建会生成唯一的id标识符,如果需要指定id可以使用如下接口

http://127.0.0.1:9200/shopping/_doc/1001

主键查询

通过指定id查询

GET http://127.0.0.1:9200/shopping/_doc/1001

响应结果

{
    "_index": "shopping",
    "_type": "_doc",
    "_id": "1001",
    "_version": 1,
    "_seq_no": 1,
    "_primary_term": 1,
    "found": true,
    "_source": {
        "title": "小米手机",
        "category": "小米",
        "images": "http://www.gulixueyuan.com/xm.jpg",
        "price": 3999.00
    }
}

全查询

GET http://127.0.0.1:9200/shopping/_search

响应结果

{
    "took": 122,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 1.0,
        "hits": [
            {
                "_index": "shopping",
                "_type": "_doc",
                "_id": "44MZkYkBpGe0S7oK7CQ2",
                "_score": 1.0,
                "_source": {
                    "title": "小米手机",
                    "category": "小米",
                    "images": "http://www.gulixueyuan.com/xm.jpg",
                    "price": 3999.00
                }
            },
            {
                "_index": "shopping",
                "_type": "_doc",
                "_id": "1001",
                "_score": 1.0,
                "_source": {
                    "title": "小米手机",
                    "category": "小米",
                    "images": "http://www.gulixueyuan.com/xm.jpg",
                    "price": 3999.00
                }
            }
        ]
    }
}

全量修改

PUT http://127.0.0.1:9200/shopping/_doc/1001

body type:json
{
    "title":"华为手机",
    "category":"华为",
    "images":"http://www.gulixueyuan.com/hw.jpg",
    "price":1999.00
}

响应结果

{
    "_index": "shopping",
    "_type": "_doc",
    "_id": "1001",
    "_version": 2,
    "result": "updated",
    "_shards": {
        "total": 2,
        "successful": 1,
        "failed": 0
    },
    "_seq_no": 2,
    "_primary_term": 1
}

局部修改

POST http://127.0.0.1:9200/shopping/_update/1001

body type:json
{
    "doc":{
        "title":"苹果手机"
    }
}

响应结果

{
    "_index": "shopping",
    "_type": "_doc",
    "_id": "1001",
    "_version": 3,
    "result": "updated",
    "_shards": {
        "total": 2,
        "successful": 1,
        "failed": 0
    },
    "_seq_no": 3,
    "_primary_term": 1
}

删除文档

DELETE http://127.0.0.1:9200/shopping/_doc/1001

响应结果

{
    "_index": "shopping",
    "_type": "_doc",
    "_id": "1001",
    "_version": 4,
    "result": "deleted",
    "_shards": {
        "total": 2,
        "successful": 1,
        "failed": 0
    },
    "_seq_no": 4,
    "_primary_term": 1
}