1、document数据格式

面向文档的搜索分析引擎

（1）应用系统的数据结构都是面向对象的，复杂的
（2）对象数据存储到数据库中，只能拆解开来，变为扁平的多张表，每次查询的时候还得还原回对象格式，相当麻烦
（3）ES是面向文档的，文档中存储的数据结构，与面向对象的数据结构是一样的，基于这种文档数据结构，es可以提供复杂的索引，全文检索，分析聚合等功能
（4）es的document用json数据格式来表达

对于一个实体类Employee

public class Employee {private String email;private String firstName;private String lastName;private EmployeeInfo info;private Date joinDate;
}public class EmployeeInfo {private String bio; // 性格private Integer age;private String[] interests; // 兴趣爱好
}

创建一个Employee对象

EmployeeInfo info = new EmployeeInfo();
info.setBio("curious and modest");
info.setAge(30);
info.setInterests(new String[]{"bike", "climb"});Employee employee = new Employee();
employee.setEmail("zhangsan@sina.com");
employee.setFirstName("san");
employee.setLastName("zhang");
employee.setInfo(info);
employee.setJoinDate(new Date());

employee对象：里面包含了Employee类自己的属性，还有一个EmployeeInfo对象

如果使用数据库去存储

创建两张表：employee表，employee_info表，将employee对象的数据重新拆开来，变成Employee数据和EmployeeInfo数据
employee表：id, email，first_name，last_name，join_date，4个字段
employee_info表：bio，age，interests，3个字段；此外还有一个外键字段，比如employee_id，关联着employee表

这样很麻烦了

如果使用es去存储

再复杂的对象都可以使用一个document去表示

{"email":      "zhangsan@sina.com","first_name": "san","last_name": "zhang","info": {"bio":         "curious and modest","age":         30,"interests": [ "bike", "climb" ]},"join_date": "2017/01/01"
}

我们就明白了es的document数据格式和数据库的关系型数据格式的区别

数据格式

Elasticsearch 是面向文档型数据库，一条数据在这里就是一个文档。 为了方便大家理解，
我们将 Elasticsearch 里存储文档数据和关系型数据库 MySQL 存储数据的概念进行一个类比

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。

RESTful

REST 指的是一组架构约束条件和原则。满足这些约束条件和原则的应用程序或设计就
是 RESTful。 Web 应用程序最重要的 REST 原则是，客户端和服务器之间的交互在请求之
间是无状态的。从客户端到服务器的每个请求都必须包含理解请求所必需的信息。如果服务
器在请求之间的任何时间点重启，客户端不会得到通知。此外，无状态请求可以由任何可用
服务器回答，这十分适合云计算之类的环境。客户端可以缓存数据以改进性能。
在服务器端，应用程序状态和功能可以分为各种资源。资源是一个有趣的概念实体，它
向客户端公开。资源的例子有：应用程序对象、数据库记录、算法等等。每个资源都使用 URI
(Universal Resource Identifier) 得到一个唯一的地址。所有资源都共享统一的接口，以便在客
户端和服务器之间传输状态。使用的是标准的 HTTP 方法，比如 GET、 PUT、 POST 和
DELETE。
在 REST 样式的 Web 服务中，每个资源都有一个地址。资源本身都是方法调用的目
标，方法列表对所有资源都是一样的。这些方法都是标准方法，包括 HTTP GET、 POST、
PUT、 DELETE，还可能包括 HEAD 和 OPTIONS。简单的理解就是，如果想要访问互联
网上的资源，就必须向资源所在的服务器发出请求，请求体中必须包含资源的网络路径， 以
及对资源进行的操作(增删改查)。

2、电商网站商品管理案例背景介绍

有一个电商网站，需要为其基于ES构建一个后台系统，提供以下功能：

（1）对商品信息进行CRUD（增删改查）操作
（2）执行简单的结构化查询
（3）可以执行简单的全文检索，以及复杂的phrase（短语）检索
（4）对于全文检索的结果，可以进行高亮显示
（5）对数据进行简单的聚合分析

3、简单的集群管理

（1）快速检查集群的健康状况

es提供了一套api，叫做cat api，可以查看es中各种各样的数据

查看集群的健康状态：

GET /_cat/health?v

响应结果

epoch      timestamp cluster       status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1635864788 22:53:08  elasticsearch yellow          1         1      1   1    0    0        1             0                  -                 50.0%

如何快速了解集群的健康状况？

green：每个索引的primary shard和replica shard都是active状态的
yellow：每个索引的primary shard都是active状态的，但是部分replica shard不是active状态，处于不可用的状态
red：不是所有索引的primary shard都是active状态的，部分索引有数据丢失了

为什么现在会处于一个yellow状态？

我们现在就一个笔记本电脑，就启动了一个es进程，相当于就只有一个node。现在es中有一个index，就是kibana自己内置建立的index。由于默认的配置是给每个index分配5个primary shard和5个replica shard，而且primary shard和replica shard不能在同一台机器上（为了容错）。现在kibana自己建立的index是1个primary shard和1个replica shard。当前就一个node，所以只有1个primary shard被分配了和启动了，但是一个replica shard没有第二台机器去启动。

做一个小实验：此时只要启动第二个es进程，就会在es集群中有2个node，然后那1个replica shard就会自动分配过去，然后cluster status就会变成green状态。

我们再解压一个es

启动es,此时端口号是9201

再次查看集群的健康状态：

GET /_cat/health?v

响应结果

epoch      timestamp cluster       status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1635865517 23:05:17  elasticsearch green           2         2      2   1    0    0        0             0                  -                100.0%

实际上在学习中并不需要启动那么多节点，可以停掉第二台es。

2）快速查看集群中有哪些索引

?v - 显示题头

GET /_cat/indices?v

响应结果

health status index   uuid                   pri rep docs.count docs.deleted store.size pri.store.size
yellow open   .kibana 7gzEC7M5SLWUhd52buBAkw   1   1          1            0      3.2kb          3.2kb

.kibana是kibana默认创建的索引

表头	含义
health	当前服务器健康状态： green(集群完整) yellow(单点正常、集群不完整) red(单点不正常)
status	索引打开、关闭状态
index	索引名
uuid	索引统一编号
pri	主分片数量
rep	副本数量
docs.count	可用文档数量
docs.deleted	文档删除状态（逻辑删除）
store.size	主分片和副分片整体占空间大小
pri.store.size	主分片占空间大小

（3）简单的索引操作

创建索引

?pretty - 格式化输出

PUT /test_index?pretty

响应结果

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

解释

{
"acknowledged"【响应结果】 : true, # true 操作成功
"shards_acknowledged"【分片结果】 : true, # 分片操作成功
"index"【索引名称】 : "test_index"
}

注意：创建索引库的分片数在 7.0.0 之前的 Elasticsearch 版本中，默认 5 片；在7.0.0之后默认 1 片

如果重复添加索引，会返回错误信息 “index [test_index/-kQoG72UTkm5L0GlVYFm7w] already exists”,

{"error": {"root_cause": [{"type": "index_already_exists_exception","reason": "index [test_index/-kQoG72UTkm5L0GlVYFm7w] already exists","index_uuid": "-kQoG72UTkm5L0GlVYFm7w","index": "test_index"}],"type": "index_already_exists_exception","reason": "index [test_index/-kQoG72UTkm5L0GlVYFm7w] already exists","index_uuid": "-kQoG72UTkm5L0GlVYFm7w","index": "test_index"},"status": 400
}

put具有幂等性，而且创建索引不支持post

POST /test_index?pretty

响应结果

No handler found for uri [/test_index?pretty] and method [POST]

查看单个索引

GET /test_index?pretty

响应结果

{"test_index": {"aliases": {},"mappings": {},"settings": {"index": {"creation_date": "1635866355428","number_of_shards": "5","number_of_replicas": "1","uuid": "-kQoG72UTkm5L0GlVYFm7w","version": {"created": "5060099"},"provided_name": "test_index"}}}
}

说明

{"shopping"【索引名】: {"aliases"【别名】: {},"mappings"【映射】: {},"settings"【设置】: {"index"【设置 - 索引】: {"creation_date"【设置 - 索引 - 创建时间】: "1635866355428","number_of_shards"【设置 - 索引 - 主分片数量】: "5",   #7.0.0之前为5，7.0.0之后为1"number_of_replicas"【设置 - 索引 - 副分片数量】: "1","uuid"【设置 - 索引 - 唯一标识】: "-kQoG72UTkm5L0GlVYFm7w","version"【设置 - 索引 - 版本】: {"created": "5060099"},"provided_name"【设置 - 索引 - 名称】: "test_index"}}}
}

删除索引

DELETE /test_index?pretty

响应结果

{"acknowledged": true
}

已经删除索引，再次删除

{"error": {"root_cause": [{"type": "index_not_found_exception","reason": "no such index","resource.type": "index_or_alias","resource.id": "test_index","index_uuid": "_na_","index": "test_index"}],"type": "index_not_found_exception","reason": "no such index","resource.type": "index_or_alias","resource.id": "test_index","index_uuid": "_na_","index": "test_index"},"status": 404
}

4、商品文档的CRUD操作

对文档的增删改查，这里的文档可以类比为关系型数据库中的表数据，添加的数据格式为 JSON 格式

（1）新增商品：新增文档，建立索引

PUT /index/type/id
{"json数据"
}

新增商品

PUT /ecommerce/product/1
{"name" : "gaolujie yagao","desc" :  "gaoxiao meibai","price" :  30,"producer" :      "gaolujie producer","tags": [ "meibai", "fangzhu" ]
}

响应结果

{"_index": "ecommerce","_type": "product","_id": "1","_version": 1,"result": "created","_shards": {"total": 2,"successful": 1,"failed": 0},"created": true
}

说明

{"_index"【索引】: "ecommerce","_type"【类型 - 文档】: "product","_id"【唯一标识】: "1", #可以类比为 MySQL 中的主键， 随机生成 "_version"【版本】: 1,"result"【结果】: "created", #这里的 create 表示创建成功 "_shards"【分片】: {"total"【分片 - 总数】: 2,"successful"【分片 - 成功】: 1,"failed"【分片 - 失败】: 0},"created": true
}

上面的数据创建后，如果没有指定数据唯一性标识（ID），默认情况下， ES 服务器会随机
生成一个。创建内容相同的文档，id是不同的，所以创建文档不支持put，put具有幂等性

POST /ecommerce/product

如果增加数据时明确数据主键，那么请求方式也可以为 PUT

PUT /ecommerce/product/1

再多新增几个商品

PUT /ecommerce/product/2
{"name" : "jiajieshi yagao","desc" :  "youxiao fangzhu","price" :  25,"producer" :      "jiajieshi producer","tags": [ "fangzhu" ]
}

PUT /ecommerce/product/3
{"name" : "zhonghua yagao","desc" :  "caoben zhiwu","price" :  40,"producer" :      "zhonghua producer","tags": [ "qingxin" ]
}

es会自动建立index和type，不需要提前创建，而且es默认会对document每个field都建立倒排索引，让其可以被搜索

（2）查询商品：检索文档

主键查询

查看文档时，需要指明文档的唯一性标识，类似于 MySQL 中数据的主键查询

GET /index/type/id

查询商品

GET /ecommerce/product/1

响应结果

{"_index": "ecommerce","_type": "product","_id": "1","_version": 1,"found": true,"_source": {"name": "gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}
}

说明

{"_index"【索引】: "ecommerce","_type"【文档类型】: "product","_id": "1","_version": 1,"found"【查询结果】: true, #true 表示查找到， false 表示未查找到 "_source"【文档源信息】: {"name": "gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}
}

全查询

_search -搜索全部

GET /ecommerce/product/_search

响应结果

{"took": 3,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 3,"max_score": 1,"hits": [{"_index": "ecommerce","_type": "product","_id": "2","_score": 1,"_source": {"name": "jiajieshi yagao","desc": "youxiao fangzhu","price": 25,"producer": "jiajieshi producer","tags": ["fangzhu"]}},{"_index": "ecommerce","_type": "product","_id": "1","_score": 1,"_source": {"name": "gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}},{"_index": "ecommerce","_type": "product","_id": "3","_score": 1,"_source": {"name": "zhonghua yagao","desc": "caoben zhiwu","price": 40,"producer": "zhonghua producer","tags": ["qingxin"]}}]}
}

（3）修改商品：替换文档（全量修改）

替换方式有一个不好，必须带上所有的field，才能去进行信息的修改

PUT /ecommerce/product/1
{"name" : "jiaqiangban gaolujie yagao","desc" :  "gaoxiao meibai","price" :  30,"producer" :      "gaolujie producer","tags": [ "meibai", "fangzhu" ]
}

响应结果

{"_index": "ecommerce","_type": "product","_id": "1","_version": 2,"result": "updated","_shards": {"total": 2,"successful": 1,"failed": 0},"created": false
}

修改之前的数据

{"_index": "ecommerce","_type": "product","_id": "1","_version": 1,"found": true,"_source": {"name": "gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}
}

修改后的数据

{"_index": "ecommerce","_type": "product","_id": "1","_version": 2,"found": true,"_source": {"name": "jiaqiangban gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}
}

如果请求体变化，比如只带上一个field，会将原有的数据内容覆盖

PUT /ecommerce/product/1
{"name" : "jiaqiangban gaolujie yagao"
}

响应结果

{"_index": "ecommerce","_type": "product","_id": "1","_version": 3,"result": "updated","_shards": {"total": 2,"successful": 1,"failed": 0},"created": false
}

查看文档

{"_index": "ecommerce","_type": "product","_id": "1","_version": 3,"found": true,"_source": {"name": "jiaqiangban gaolujie yagao"}
}

再次替换回原来的文档

PUT /ecommerce/product/1
{"name" : "jiaqiangban gaolujie yagao","desc" :  "gaoxiao meibai","price" :  30,"producer" :      "gaolujie producer","tags": [ "meibai", "fangzhu" ]
}

查看文档

{"_index": "ecommerce","_type": "product","_id": "1","_version": 4,"found": true,"_source": {"name": "gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}
}

（4）修改商品：更新文档（局部修改）

可以修改指定的field

POST /ecommerce/product/1/_update
{"doc": {"name": "jiaqiangban gaolujie yagao"}
}

响应结果

{"_index": "ecommerce","_type": "product","_id": "1","_version": 5,"result": "updated","_shards": {"total": 2,"successful": 1,"failed": 0},"created": false
}

修改之前的数据

{"_index": "ecommerce","_type": "product","_id": "1","_version": 4,"found": true,"_source": {"name": "gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}
}

修改之后的数据

{"_index": "ecommerce","_type": "product","_id": "1","_version": 6,"found": true,"_source": {"name": "jiaqiangban gaolujie yagao","desc": "gaoxiao meibai","price": 30,"producer": "gaolujie producer","tags": ["meibai","fangzhu"]}
}

（5）删除商品：删除文档

删除一个文档其实不会立即从磁盘上移除，它只是被标记成已删除（逻辑删除）。

主键删除

DELETE /ecommerce/product/1

响应结果

{"found": true,"_index": "ecommerce","_type": "product","_id": "1","_version": 7,"result": "deleted","_shards": {"total": 2,"successful": 1,"failed": 0}
}

查看商品

GET /ecommerce/product/1

响应结果

{"_index": "ecommerce","_type": "product","_id": "1","found": false
}

条件删除文档

一般删除数据都是根据文档的唯一性标识进行删除，实际操作时，也可以根据条件对多条数据进行删除

先查看当前全部文档

GET /ecommerce/product/_search

响应结果

{"took": 1,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 2,"max_score": 1,"hits": [{"_index": "ecommerce","_type": "product","_id": "2","_score": 1,"_source": {"name": "jiajieshi yagao","desc": "youxiao fangzhu","price": 25,"producer": "jiajieshi producer","tags": ["fangzhu"]}},{"_index": "ecommerce","_type": "product","_id": "3","_score": 1,"_source": {"name": "zhonghua yagao","desc": "caoben zhiwu","price": 40,"producer": "zhonghua producer","tags": ["qingxin"]}}]}
}

删除price=40的所有商品

POST /ecommerce/product/_delete_by_query
{"query": {"match": {"price": 40}}
}

响应结果

{"took": 322,"timed_out": false,"total": 1,"deleted": 1,"batches": 1,"version_conflicts": 0,"noops": 0,"retries": {"bulk": 0,"search": 0},"throttled_millis": 0,"requests_per_second": -1,"throttled_until_millis": 0,"failures": []
}

再次查询商品

{"took": 1,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 1,"max_score": 1,"hits": [{"_index": "ecommerce","_type": "product","_id": "2","_score": 1,"_source": {"name": "jiajieshi yagao","desc": "youxiao fangzhu","price": 25,"producer": "jiajieshi producer","tags": ["fangzhu"]}}]}
}