前言
在《Elasticsearch 之（2）Elasticsearch核心概念》中简单提到了document 和 数据库db 数据模型的差别，本文将详细讲述集中常用的数据模型。文件搜索数据建模，对类似文件系统这种的有多层级关系的数据进行建模
1、文件系统数据构造
PUT /fs
{
"settings": {
"analysis": {
"analyzer": {
"paths": {
"tokenizer": "path_hierarchy"
}
}
}
}
}path_hierarchy tokenizer讲解
/a/b/c/d --> path_hierarchy -> /a/b/c/d, /a/b/c, /a/b, /a
fs: filesystem
PUT /fs/_mapping/file
{
"properties": {
"name": {
"type": "keyword"
},
"path": {
"type": "keyword",
"fields": {
"tree": {
"type": "text",
"analyzer": "paths"
}
}
}
}
}PUT /fs/file/1
{
"name": "README.txt",
"path": "/workspace/projects/helloworld",
"contents": "这是我的第一个elasticsearch程序"
}2、对文件系统执行搜索
文件搜索需求：查找一份，内容包括elasticsearch，在/workspace/projects/hellworld这个目录下的文件
GET /fs/file/_search
{
"query": {
"bool": {
"must": [
{
"match": {
"contents": "elasticsearch"
}
},
{
"constant_score": {
"filter": {
"term": {
"path": "/workspace/projects/helloworld"
}
}
}
}
]
}
}
}{
"took": 2,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1.284885,
"hits": [
{
"_index": "fs",
"_type": "file",
"_id": "1",
"_score": 1.284885,
"_source": {
"name": "README.txt",
"path": "/workspace/projects/helloworld",
"contents": "这是我的第一个elasticsearch程序"
}
}
]
}
}搜索需求2：搜索/workspace目录下，内容包含elasticsearch的所有的文件
/workspace/projects/helloworld doc1
/workspace/projects doc1
/workspace doc1
GET /fs/file/_search
{
"query": {
"bool": {
"must": [
{
"match": {
"contents": "elasticsearch"
}
},
{
"constant_score": {
"filter": {
"term": {
"path.tree": "/workspace"
}
}
}
}
]
}
}
}嵌套关系
1、做一个实验，引出来为什么需要nested object
冗余数据方式的来建模，其实用的就是object类型，我们这里又要引入一种新的object类型，nested object类型
博客，评论，做的这种数据模型
PUT /website/blogs/6
{
"title": "花无缺发表的一篇帖子",
"content": "我是花无缺，大家要不要考虑一下投资房产和买股票的事情啊。。。",
"tags": [ "投资", "理财" ],
"comments": [
{
"name": "小鱼儿",
"comment": "什么股票啊？推荐一下呗",
"age": 28,
"stars": 4,
"date": "2016-09-01"
},
{
"name": "黄药师",
"comment": "我喜欢投资房产，风，险大收益也大",
"age": 31,
"stars": 5,
"date": "2016-10-22"
}
]
}被年龄是28岁的黄药师评论过的博客，搜索
GET /website/blogs/_search
{
"query": {
"bool": {
"must": [
{ "match": { "comments.name": "黄药师" }},
{ "match": { "comments.age": 28 }}
]
}
}
}{
"took": 102,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1.8022683,
"hits": [
{
"_index": "website",
"_type": "blogs",
"_id": "6",
"_score": 1.8022683,
"_source": {
"title": "花无缺发表的一篇帖子",
"content": "我是花无缺，大家要不要考虑一下投资房产和买股票的事情啊。。。",
"tags": [
"投资",
"理财"
],
"comments": [
{
"name": "小鱼儿",
"comment": "什么股票啊？推荐一下呗",
"age": 28,
"stars": 4,
"date": "2016-09-01"
},
{
"name": "黄药师",
"comment": "我喜欢投资房产，风，险大收益也大",
"age": 31,
"stars": 5,
"date": "2016-10-22"
}
]
}
}
]
}
}结果是。。。好像不太对啊？？？
object类型数据结构的底层存储。。。
{
"title": [ "花无缺", "发表", "一篇", "帖子" ],
"content": [ "我", "是", "花无缺", "大家", "要不要", "考虑", "一下", "投资", "房产", "买", "股票", "事情" ],
"tags": [ "投资", "理财" ],
"comments.name": [ "小鱼儿", "黄药师" ],
"comments.comment": [ "什么", "股票", "推荐", "我", "喜欢", "投资", "房产", "风险", "收益", "大" ],
"comments.age": [ 28, 31 ],
"comments.stars": [ 4, 5 ],
"comments.date": [ 2016-09-01, 2016-10-22 ]
}object类型底层数据结构，会将一个json数组中的数据，进行扁平化
所以，直接命中了这个document，name=黄药师，age=28，正好符合
2、引入nested object类型，来解决object类型底层数据结构导致的问题
修改mapping，将comments的类型从object设置为nested
PUT /website
{
"mappings": {
"blogs": {
"properties": {
"comments": {
"type": "nested",
"properties": {
"name": { "type": "string" },
"comment": { "type": "string" },
"age": { "type": "short" },
"stars": { "type": "short" },
"date": { "type": "date" }
}
}
}
}
}
}{
"comments.name": [ "小鱼儿" ],
"comments.comment": [ "什么", "股票", "推荐" ],
"comments.age": [ 28 ],
"comments.stars": [ 4 ],
"comments.date": [ 2014-09-01 ]
}
{
"comments.name": [ "黄药师" ],
"comments.comment": [ "我", "喜欢", "投资", "房产", "风险", "收益", "大" ],
"comments.age": [ 31 ],
"comments.stars": [ 5 ],
"comments.date": [ 2014-10-22 ]
}
{
"title": [ "花无缺", "发表", "一篇", "帖子" ],
"body": [ "我", "是", "花无缺", "大家", "要不要", "考虑", "一下", "投资", "房产", "买", "股票", "事情" ],
"tags": [ "投资", "理财" ]
}再次搜索，成功了。。。
GET /website/blogs/_search
{
"query": {
"bool": {
"must": [
{
"match": {
"title": "花无缺"
}
},
{
"nested": {
"path": "comments",
"score_mode": "max";
"query": {
"bool": {
"must": [
{
"match": {
"comments.name": "黄药师"
}
},
{
"match": {
"comments.age": 28
}
}
]
}
}
}
}
]
}
}
}score_mode：max，min，avg，none，默认是avg
如果搜索命中了多个nested document，如何讲个多个nested document的分数合并为一个分数
我们讲解一下基于nested object中的数据进行聚合分析
聚合数据分析的需求1：按照评论日期进行bucket划分，然后拿到每个月的评论的评分的平均值
GET /website/blogs/_search
{
"size": 0,
"aggs": {
"comments_path": {
"nested": {
"path": "comments"
},
"aggs": {
"group_by_comments_date": {
"date_histogram": {
"field": "comments.date",
"interval": "month",
"format": "yyyy-MM"
},
"aggs": {
"avg_stars": {
"avg": {
"field": "comments.stars"
}
}
}
}
}
}
}
}{
"took": 52,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 0,
"hits": []
},
"aggregations": {
"comments_path": {
"doc_count": 4,
"group_by_comments_date": {
"buckets": [
{
"key_as_string": "2016-08",
"key": 1470009600000,
"doc_count": 1,
"avg_stars": {
"value": 3
}
},
{
"key_as_string": "2016-09",
"key": 1472688000000,
"doc_count": 2,
"avg_stars": {
"value": 4.5
}
},
{
"key_as_string": "2016-10",
"key": 1475280000000,
"doc_count": 1,
"avg_stars": {
"value": 5
}
}
]
}
}
}
}当根据nested object类型聚合下钻时候，可以用过reverse_path, 获取其他object field进行下钻。
GET /website/blogs/_search
{
"size": 0,
"aggs": {
"comments_path": {
"nested": {
"path": "comments"
},
"aggs": {
"group_by_comments_age": {
"histogram": {
"field": "comments.age",
"interval": 10
},
"aggs": {
"reverse_path": {
"reverse_nested": {},
"aggs": {
"group_by_tags": {
"terms": {
"field": "tags.keyword"
}
}
}
}
}
}
}
}
}
}{
"took": 5,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 0,
"hits": []
},
"aggregations": {
"comments_path": {
"doc_count": 4,
"group_by_comments_age": {
"buckets": [
{
"key": 20,
"doc_count": 1,
"reverse_path": {
"doc_count": 1,
"group_by_tags": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "投资",
"doc_count": 1
},
{
"key": "理财",
"doc_count": 1
}
]
}
}
},
{
"key": 30,
"doc_count": 3,
"reverse_path": {
"doc_count": 2,
"group_by_tags": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "大侠",
"doc_count": 1
},
{
"key": "投资",
"doc_count": 1
},
{
"key": "理财",
"doc_count": 1
},
{
"key": "练功",
"doc_count": 1
}
]
}
}
}
]
}
}
}
}父子关系
nested object的建模，有个不好的地方，就是采取的是类似冗余数据的方式，将多个数据都放在一起了，维护成本就比较高
parent child建模方式，采取的是类似于关系型数据库的三范式类的建模，多个实体都分割开来，每个实体之间都通过一些关联方式，进行了父子关系的关联，各种数据不需要都放在一起，父doc和子doc分别在进行更新的时候，都不会影响对方
一对多关系的建模，维护起来比较方便，而且我们之前说过，类似关系型数据库的建模方式，应用层join的方式，会导致性能比较差，因为做多次搜索。父子关系的数据模型，不会，性能很好。因为虽然数据实体之间分割开来，但是我们在搜索的时候，由es自动为我们处理底层的关联关系，并且通过一些手段保证搜索性能。
父子关系数据模型，相对于nested数据模型来说，优点是父doc和子doc互相之间不会影响
要点：父子关系元数据映射，用于确保查询时候的高性能，但是有一个限制，就是父子数据必须存在于一个shard中
父子关系数据存在一个shard中，而且还有映射其关联关系的元数据，那么搜索父子关系数据的时候，不用跨分片，一个分片本地自己就搞定了，性能当然高咯
案例背景：研发中心员工管理案例，一个IT公司有多个研发中心，每个研发中心有多个员工
PUT /company
{
"mappings": {
"rd_center": {},
"employee": {
"_parent": {
"type": "rd_center"
}
}
}
}父子关系建模的核心，多个type之间有父子关系，用_parent指定父type
POST /company/rd_center/_bulk
{ "index": { "_id": "1" }}
{ "name": "北京研发总部", "city": "北京", "country": "中国" }
{ "index": { "_id": "2" }}
{ "name": "上海研发中心", "city": "上海", "country": "中国" }
{ "index": { "_id": "3" }}
{ "name": "硅谷人工智能实验室", "city": "硅谷", "country": "美国" }shard路由的时候，id=1的rd_center doc，默认会根据id进行路由，到某一个shard
PUT /company/employee/1?parent=1
{
"name": "张三",
"birthday": "1970-10-24",
"hobby": "爬山"
}维护父子关系的核心，parent=1，指定了这个数据的父doc的id
此时，parent-child关系，就确保了说，父doc和子doc都是保存在一个shard上的。内部原理还是doc routing，employee和rd_center的数据，都会用parent id作为routing，这样就会到一个shard
就不会根据id=1的employee doc的id进行路由了，而是根据parent=1进行路由，会根据父doc的id进行路由，那么就可以通过底层的路由机制，保证父子数据存在于一个shard中
POST /company/employee/_bulk
{ "index": { "_id": 2, "parent": "1" }}
{ "name": "李四", "birthday": "1982-05-16", "hobby": "游泳" }
{ "index": { "_id": 3, "parent": "2" }}
{ "name": "王二", "birthday": "1979-04-01", "hobby": "爬山" }
{ "index": { "_id": 4, "parent": "3" }}
{ "name": "赵五", "birthday": "1987-05-11", "hobby": "骑马" }我们已经建立了父子关系的数据模型之后，就要基于这个模型进行各种搜索和聚合了
1、搜索有1980年以后出生的员工的研发中心
GET /company/rd_center/_search
{
"query": {
"has_child": {
"type": "employee",
"query": {
"range": {
"birthday": {
"gte": "1980-01-01"
}
}
}
}
}
}{
"took": 33,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 1,
"hits": [
{
"_index": "company",
"_type": "rd_center",
"_id": "1",
"_score": 1,
"_source": {
"name": "北京研发总部",
"city": "北京",
"country": "中国"
}
},
{
"_index": "company",
"_type": "rd_center",
"_id": "3",
"_score": 1,
"_source": {
"name": "硅谷人工智能实验室",
"city": "硅谷",
"country": "美国"
}
}
]
}
}2、搜索有名叫张三的员工的研发中心
GET /company/rd_center/_search
{
"query": {
"has_child": {
"type": "employee",
"query": {
"match": {
"name": "张三"
}
}
}
}
}{
"took": 2,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1,
"hits": [
{
"_index": "company",
"_type": "rd_center",
"_id": "1",
"_score": 1,
"_source": {
"name": "北京研发总部",
"city": "北京",
"country": "中国"
}
}
]
}
}3、搜索有至少2个以上员工的研发中心
GET /company/rd_center/_search
{
"query": {
"has_child": {
"type": "employee",
"min_children": 2,
"query": {
"match_all": {}
}
}
}
}{
"took": 5,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1,
"hits": [
{
"_index": "company",
"_type": "rd_center",
"_id": "1",
"_score": 1,
"_source": {
"name": "北京研发总部",
"city": "北京",
"country": "中国"
}
}
]
}
}4、搜索在中国的研发中心的员工
GET /company/employee/_search
{
"query": {
"has_parent": {
"parent_type": "rd_center",
"query": {
"term": {
"country.keyword": "中国"
}
}
}
}
}{
"took": 5,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 3,
"max_score": 1,
"hits": [
{
"_index": "company",
"_type": "employee",
"_id": "3",
"_score": 1,
"_routing": "2",
"_parent": "2",
"_source": {
"name": "王二",
"birthday": "1979-04-01",
"hobby": "爬山"
}
},
{
"_index": "company",
"_type": "employee",
"_id": "1",
"_score": 1,
"_routing": "1",
"_parent": "1",
"_source": {
"name": "张三",
"birthday": "1970-10-24",
"hobby": "爬山"
}
},
{
"_index": "company",
"_type": "employee",
"_id": "2",
"_score": 1,
"_routing": "1",
"_parent": "1",
"_source": {
"name": "李四",
"birthday": "1982-05-16",
"hobby": "游泳"
}
}
]
}
}5、统计每个国家的喜欢每种爱好的员工有多少个
GET /company/rd_center/_search
{
"size": 0,
"aggs": {
"group_by_country": {
"terms": {
"field": "country.keyword"
},
"aggs": {
"group_by_child_employee": {
"children": {
"type": "employee"
},
"aggs": {
"group_by_hobby": {
"terms": {
"field": "hobby.keyword"
}
}
}
}
}
}
}
}{
"took": 15,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 3,
"max_score": 0,
"hits": []
},
"aggregations": {
"group_by_country": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "中国",
"doc_count": 2,
"group_by_child_employee": {
"doc_count": 3,
"group_by_hobby": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "爬山",
"doc_count": 2
},
{
"key": "游泳",
"doc_count": 1
}
]
}
}
},
{
"key": "美国",
"doc_count": 1,
"group_by_child_employee": {
"doc_count": 1,
"group_by_hobby": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "骑马",
"doc_count": 1
}
]
}
}
}
]
}
}
}父子关系，祖孙三层关系的数据建模，搜索
PUT /company
{
"mappings": {
"country": {},
"rd_center": {
"_parent": {
"type": "country"
}
},
"employee": {
"_parent": {
"type": "rd_center"
}
}
}
}country -> rd_center -> employee，祖孙三层数据模型
POST /company/country/_bulk
{ "index": { "_id": "1" }}
{ "name": "中国" }
{ "index": { "_id": "2" }}
{ "name": "美国" }POST /company/rd_center/_bulk
{ "index": { "_id": "1", "parent": "1" }}
{ "name": "北京研发总部" }
{ "index": { "_id": "2", "parent": "1" }}
{ "name": "上海研发中心" }
{ "index": { "_id": "3", "parent": "2" }}
{ "name": "硅谷人工智能实验室" }PUT /company/employee/1?parent=1&routing=1
{
"name": "张三",
"dob": "1970-10-24",
"hobby": "爬山"
}routing参数的讲解，必须跟grandparent相同，否则有问题
country，用的是自己的id去路由; rd_center，parent，用的是country的id去路由; employee，如果也是仅仅指定一个parent，那么用的是rd_center的id去路由，这就导致祖孙三层数据不会在一个shard上
孙子辈儿，要手动指定routing，指定为爷爷辈儿的数据的id
搜索有爬山爱好的员工所在的国家
GET /company/country/_search
{
"query": {
"has_child": {
"type": "rd_center",
"query": {
"has_child": {
"type": "employee",
"query": {
"match": {
"hobby": "爬山"
}
}
}
}
}
}
}{
"took": 10,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1,
"hits": [
{
"_index": "company",
"_type": "country",
"_id": "1",
"_score": 1,
"_source": {
"name": "中国"
}
}
]
}
}