本文属于极客时间Elasticsearch核心技术与实战学习笔记系列。
对象和 Nested 对象的局限性
ES 提供了类似关系型数据库中 Join 的实现。使用 Join 数据类型实现,可以通过 Parent / Child 的关系,从而分离两个对象
定义父子关系的几个步骤
设置 Mapping
索引父文档
创建索引
DELETE my_blogs
# 设定 Parent/Child Mapping
PUT my_blogs
{
"settings": {
"number_of_shards": 2
},
"mappings": {
"properties": {
"blog_comments_relation": {
"type": "join",
"relations": {
"blog": "comment"
}
},
"content": {
"type": "text"
},
"title": {
"type": "keyword"
}
}
}
}
索引父文档
#索引父文档
PUT my_blogs/_doc/blog1
{
"title":"Learning Elasticsearch",
"content":"learning ELK @ geektime",
"blog_comments_relation":{
"name":"blog"
}
}
#索引父文档
PUT my_blogs/_doc/blog2
{
"title":"Learning Hadoop",
"content":"learning Hadoop",
"blog_comments_relation":{
"name":"blog"
}
}
#索引子文档
PUT my_blogs/_doc/comment1?routing=blog1
{
"comment":"I am learning ELK",
"username":"Jack",
"blog_comments_relation":{
"name":"comment",
"parent":"blog1"
}
}
#索引子文档
PUT my_blogs/_doc/comment2?routing=blog2
{
"comment":"I like Hadoop!!!!!",
"username":"Jack",
"blog_comments_relation":{
"name":"comment",
"parent":"blog2"
}
}
#索引子文档
PUT my_blogs/_doc/comment3?routing=blog2
{
"comment":"Hello Hadoop",
"username":"Bob",
"blog_comments_relation":{
"name":"comment",
"parent":"blog2"
}
}
Parent / Child 所支持的查询
#根据父文档ID查看
GET my_blogs/_doc/blog2
#返回
{
"_index" : "my_blogs",
"_type" : "_doc",
"_id" : "blog2",
"_version" : 1,
"_seq_no" : 1,
"_primary_term" : 1,
"found" : true,
"_source" : {
"title" : "Learning Hadoop",
"content" : "learning Hadoop",
"blog_comments_relation" : {
"name" : "blog"
}
}
}
Parent Id 查询 :这里就是通过blog查询评论的信息
# Has Child 查询,返回父文档:demo就是通过评查询blog信息 ,
#通过ID ,访问子文档
GET my_blogs/_doc/comment3
{
"_index" : "my_blogs",
"_type" : "_doc",
"_id" : "comment3",
"found" : false
}