网站后台管理系统cms/培训网络营销的机构

es基于lucene实现。https://www.elastic.co/guide/cn/elasticsearch/guide/current/index.html

es文档元数据
一个文档不三个必须的元数据元素如下：
_index
文档在哪存放。一个 索引 应该是因共同的特性被分组到一起的文档集合。
_type
文档表示的对象类别。索引子分区。
_id
文档唯一标识。可以用户自定义或者自动生成.自动生成的 ID 是 URL-safe、 基于 Base64 编码且长度为20个字符的 GUID 字符串。 这些 GUID 字符串由可修改的 FlakeID 模式生成，这种模式允许多个节点并行生成唯一 ID ，且互相之间的冲突概率几乎为零。

非必须的元素:

_version，记录文档版本号。在 Elasticsearch 中每个文档都有一个版本号。当每次对文档进行修改时（包括删除）， _version 的值会递增。

es查询结果标识

took：查询话费时间；

shards：查询过程参与的分片数。

timeout：是否超时，timeout时间可以设置：

GET /_search?timeout=10ms

hits:

total:它 包含 total 字段来表示匹配到的文档总数，并且一个 hits 数组包含所查询结果的前十个文档。

每个结果还有一个 _score ，它衡量了文档与查询的匹配程度。默认情况下，首先返回最相关的文档结果，就是说，返回的文档是按照 _score 降序排列的。在这个例子中，我们没有指定任何查询，故所有的文档具有相同的相关性，因此对所有的结果而言 1 是中性的 _score 。max_score 值是与查询所匹配文档的 _score 的最大值。

t@ubuntu:~$ curl -XGET 'localhost:9200/_search?pretty'
{"took" : 759,"timed_out" : false,"_shards" : {"total" : 5,"successful" : 5,"failed" : 0},"hits" : {"total" : 3,"max_score" : 1.0,"hits" : [{"_index" : "website","_type" : "blog","_id" : "123","_score" : 1.0,"_source" : {"title" : "My first blog entry","text" : "I am starting to get the hang of this...","date" : "2014/01/02"}},{"_index" : "website","_type" : "blog","_id" : "AV6ZDic0Gtb1Pf5XS4Nu","_score" : 1.0,"_source" : {"title" : "My second blog entry","text" : "Still trying this out...","date" : "2014/01/01"}},{"_index" : "website","_type" : "blog","_id" : "1","_score" : 1.0,"_source" : {"title" : "My first blog entry","text" : "Starting to get the hang of this...","views" : 2,"tags" : ["testing"]}}]}
}

es增删改查

1,保存文档

PUT /website/blog/123
{"title": "My first blog entry","text":  "Just trying this out...","date":  "2014/01/01"
}

2，查询文档

  根据id查询

GET /website/blog/123?pretty

查询部分字段，仅查询title和text字段

GET /website/blog/123?_source=title,text

查询结果不需要元数据

GET /website/blog/123/_source

查询文档是否存在

curl -i -XHEAD http://localhost:9200/website/blog/123

存在：200

不存在:404

搜索返回指定字段

http://ip:9200/index/type/_search?_source=createTime

查询多个文档：

GET /_mget
{"docs" : [{"_index" : "website","_type" :  "blog","_id" :    2},{"_index" : "website","_type" :  "pageviews","_id" :    1,"_source": "views"}]
}

多索引，多类型查询：

/_search
在所有的索引中搜索所有的类型
/gb/_search
在 gb 索引中搜索所有的类型
/gb,us/_search
在 gb 和 us 索引中搜索所有的文档
/g*,u*/_search
在任何以 g 或者 u 开头的索引中搜索所有的类型
/gb/user/_search
在 gb 索引中搜索 user 类型
/gb,us/user,tweet/_search
在 gb 和 us 索引中搜索 user 和 tweet 类型
/_all/user,tweet/_search
在所有的索引中搜索 user 和 tweet 类型

分页:

GET /_search?size=5&from=10

http://localhost:9200/ct_ws/type/_search?sort=createTime:desc&pretty&size=20000&from=0&_source=createTime,url

3，修改文档

根据id，再传一次文档就好,version值会自动递增

PUT /website/blog/123
{"title": "My first blog entry","text":  "I am starting to get the hang of this...","date":  "2014/01/02"
}

t@ubuntu:~$ curl -XPUT 'localhost:9200/website/blog/123?pretty' -H 'Content-Type: application/json' -d'
> {
>   "title": "My first blog entry",
>   "text":  "I am starting to get the hang of this...",
>   "date":  "2014/01/02"
> }
> '
{"_index" : "website","_type" : "blog","_id" : "123","_version" : 2,"result" : "updated","_shards" : {"total" : 2,"successful" : 1,"failed" : 0},"created" : false
}

在es内部，旧文档会被删除，新文档重新索引 ；

根据id新增字段

POST /website/blog/1/_update
{"doc" : {"tags" : [ "testing" ],"views": 0}
}

根据id修改字段，让views值增1

POST /website/blog/1/_update
{"script" : "ctx._source.views+=1"
}

eg:

t@ubuntu:~$ curl -XPOST 'localhost:9200/website/blog/1/_update?pretty' -H 'Content-Type: application/json' -d'
{"script" : "ctx._source.views+=1"
}
'
{"_index" : "website","_type" : "blog","_id" : "1","_version" : 5,"result" : "updated","_shards" : {"total" : 2,"successful" : 1,"failed" : 0}
}
t@ubuntu:~$ curl -XGET 'localhost:9200/website/blog/1?pretty'                                                 
{"_index" : "website","_type" : "blog","_id" : "1","_version" : 5,"found" : true,"_source" : {"title" : "My first blog entry","text" : "Starting to get the hang of this...","views" : 2,"tags" : ["testing"]}
}
t@ubuntu:~$ 

4，删除文档

删除文档不会立即将文档从磁盘中删除，只是将文档标记为已删除状态

根据id删除文档

DELETE /website/blog/123

批量操作

POST /_bulk
{ "delete": { "_index": "website", "_type": "blog", "_id": "123" }} 
{ "create": { "_index": "website", "_type": "blog", "_id": "123" }}
{ "title":    "My first blog post" }
{ "index":  { "_index": "website", "_type": "blog" }}
{ "title":    "My second blog post" }
{ "update": { "_index": "website", "_type": "blog", "_id": "123", "_retry_on_conflict" : 3} }
{ "doc" : {"title" : "My updated blog post"} } 

清空索引数据,类似于mysql的drop talble操作

curl -XPOST 'http://ip:9600/megacorp/employee/_delete_by_query' -H 'Content-Type: application/json' -d'
{"query": {"match_all": {}}
}
'

并发控制

es通过version对并发读写进行控制:

对已经创建的文档，只有versin=1时才修改

PUT /website/blog/1?version=1 
{"title": "My first blog entry","text":  "Starting to get the hang of this..."
}

如果version值不一致，会引发报错：

t@ubuntu:~$ 
t@ubuntu:~$ curl -XPUT 'localhost:9200/website/blog/1?version=1&pretty' -H 'Content-Type: application/json' -d'
> {
>   "title": "My first blog entry",
>   "text":  "Starting to get the hang of this..."
> }
> '
{"error" : {"root_cause" : [{"type" : "version_conflict_engine_exception","reason" : "[blog][1]: version conflict, current version [2] is different than the one provided [1]","index_uuid" : "aGPDbTmcTjKyhQ4fEJ6NEw","shard" : "3","index" : "website"}],"type" : "version_conflict_engine_exception","reason" : "[blog][1]: version conflict, current version [2] is different than the one provided [1]","index_uuid" : "aGPDbTmcTjKyhQ4fEJ6NEw","shard" : "3","index" : "website"},"status" : 409
}
t@ubuntu:~$ 

使用外部版本号：

PUT /website/blog/2?version=5&version_type=external
{"title": "My first external blog entry","text":  "Starting to get the hang of this..."
}