快速入门案例实战：电商网站商品管理（一）
内容来自中华石杉在B站的Elasticsearch 顶尖高手系列课程核心知识篇，其中部分代码从 Elasticsearch 5.2 升级到 7.10.1
1. document 数据格式
面向文档的搜索分析引擎
public class Employee {
private String email;
private String firstName;
private String lastName;
private EmployeeInfo info;
private Date joinDate;
}
private class EmployeeInfo {
private String bio; // 性格
private Integer age;
private String[] interests; // 兴趣爱好
}
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
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：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
Elasticsearch 的 document 数据格式（JSON）和数据库的关系型数据格式的区别
{
"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"
}2. 电商网站商品管理案例背景介绍
假设有一个电商网站，需要为其基于 Elasticsearch 构建一个后台系统，提供以下功能：
3. 简单的集群管理
Elasticsearch 提供了一套 api，叫做 cat api，可以查看 Elasticsearch中各种各样的数据
GET /_cat/health?v
# 7.10.1
epoch timestamp cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1609986928 02:35:28 study-application green 1 1 6 6 0 0 0 0 - 100.0%
# 5.2
epoch timestamp cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1488006741 15:12:21 elasticsearch yellow 1 1 1 1 0 0 1 0 - 50.0%
epoch timestamp cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1488007113 15:18:33 elasticsearch green 2 2 2 1 0 0 0 0 - 100.0%
epoch timestamp cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1488007216 15:20:16 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、yellow、red
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 Elasticsearch 进程，就会在 Elasticsearch 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。
GET /_cat/indices?v
# 7.10.1
health status index uuid pri rep docs.count docs.deleted store.size pri.store.size
green open .apm-custom-link -cHKkvF8S_um5DOZUKSZEA 1 0 0 0 208b 208b
green open .kibana_task_manager_1 UPJGtaocRaykb09d8QoPoA 1 0 5 3570 420.3kb 420.3kb
green open .apm-agent-configuration yIuKhjPES8O6rATBYWuChA 1 0 0 0 208b 208b
green open .kibana-event-log-7.10.1-000001 OEvvbMYIRfacpDICarEBZw 1 0 1 0 5.6kb 5.6kb
green open .kibana_1 D1uIPOjURDquh-msVgkG9Q 1 0 21 2 2.1mb 2.1mb
# 5.2
health status index uuid pri rep docs.count docs.deleted store.size pri.store.size
yellow open .kibana rUm9n9wMRQCCrRDEhqneBg 1 1 1 0 3.1kb 3.1kb创建索引：PUT /test_index?pretty
PUT /test_index?pretty
{
"acknowledged" : true,
"shards_acknowledged" : true,
"index" : "test_index"
}
GET _cat/indices?v
# 7.10.1
health status index uuid pri rep docs.count docs.deleted store.size pri.store.size
...
yellow open test_index X_bJ1tT-TWW-3i-d1Mpy9Q 1 1 0 0 208b 208b
# 5.2
health status index uuid pri rep docs.count docs.deleted store.size pri.store.size
yellow open test_index XmS9DTAtSkSZSwWhhGEKkQ 5 1 0 0 650b 650b
yellow open .kibana rUm9n9wMRQCCrRDEhqneBg 1 1 1 0 3.1kb 3.1kb删除索引：DELETE /test_index?pretty
DELETE /test_index?pretty
{
"acknowledged" : true
}新增商品：新增文档，建立索引
PUT /ecommerce/product/1
{
"name" : "gaolujie yagao",
"desc" : "gaoxiao meibai",
"price" : 30,
"producer" :"gaolujie producer",
"tags": [ "meibai", "fangzhu" ]
}
#! Deprecation: [types removal] Specifying types in document index requests is deprecated, use the typeless endpoints instead (/{index}/_doc/{id}, /{index}/_doc, or /{index}/_create/{id}).
PUT /ecommerce/_doc/4
{
"name" : "heiren yagao",
"desc" : "zhiwu",
"price" : 50,
"producer" : "heiren producer",
"tags": [ "buohe" ]
}
PUT /ecommerce/_doc
{
"name" : "shuermin yagao",
"desc" : "mingan",
"price" : 60,
"producer" : "shuermin producer",
"tags": [ "mingan" ]
}
{
"error" : "Incorrect HTTP method for uri [/ecommerce/_doc?pretty=true] and method [PUT], allowed: [POST]",
"status" : 405
}
POST /ecommerce/_doc
{
"name" : "shuermin yagao",
"desc" : "mingan",
"price" : 60,
"producer" : "shuermin producer",
"tags": [ "mingan" ]
}
POST /ecommerce/_create/6
{
"name" : "Listerine mouthwash",
"desc" : "cool mint",
"price" : 60,
"producer" : "qiangsheng producer",
"tags": [ "mint" ]
}ES 会自动建立 index 和 type，不需要提前创建，而且
查询商品：检索文档
GET /ecommerce/product/1
#! Deprecation: [types removal] Specifying types in document get requests is deprecated, use the /{index}/_doc/{id} endpoint instead.修改商品：替换文档
PUT /ecommerce/_doc/1
{
"name" : "jiaqiangban gaolujie yagao",
"desc" : "gaoxiao meibai",
"price" : 30,
"producer" :"gaolujie producer",
"tags": [ "meibai", "fangzhu" ]
}替换方式有一个不好，即使必须带上所有的field，才能去进行信息的修改
修改商品：更新文档
POST /ecommerce/_update/1
{
"doc": {
"name" : "update post"
}
}在执行 POST update 操作的时候，如果内容不变的化，版本是不会增加的。
删除商品：删除文档
DELETE /ecommerce/_doc/1