Elasticsearch 7.x文档基本操作（CRUD）

官方文档：
https://www.elastic.co/guide/en/elasticsearch/reference/current/docs.html

1、添加文档

1.1、指定文档ID

PUT blog/_doc/1
{
  "title":"1、VMware Workstation虚拟机软件安装图解",
  "author":"chengyuqiang",
  "content":"1、VMware Workstation虚拟机软件安装图解...",
  "url":"http://x.co/6nc81"
}

Elasticsearch服务会返回一个JSON格式的响应。

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 0,
  "_primary_term" : 2
}

响应结果说明：

• _index：文档所在的索引名
• _type：文档所在的类型名
• _id：文档ID
• _version：文档的版本
• result：created已经创建
• _shards： _shards表示索引操作的复制过程的信息。
• total：指示应在其上执行索引操作的分片副本（主分片和副本分片）的数量。
• successful：表示索引操作成功的分片副本数。
• failed：在副本分片上索引操作失败的情况下包含复制相关错误。

1.2、不指定文档ID
添加文档时可以不指定文档id，则文档id是自动生成的字符串。注意，需要使用POST方法，而不是PUT方法。

POST blog/_doc
{
  "title":"2、Linux服务器安装图解",
  "author":"chengyuqiang",
  "content":"2、Linux服务器安装图解解...",
  "url":"http://x.co/6nc82"
}

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "5P2-O2gBNSQY7o-KMw2P",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 1,
  "_primary_term" : 1
}

2、获取文档

2.1、通过文档id获取指定的文档

GET blog/_doc/1

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 1,
  "found" : true,
  "_source" : {
    "title" : "1、VMware Workstation虚拟机软件安装图解",
    "author" : "chengyuqiang",
    "content" : "1、VMware Workstation虚拟机软件安装图解...",
    "url" : "http://x.co/6nc81"
  }
}

响应结果说明：

• found值为true，表明查询到该文档
• _source字段是文档的内容

2.2、文档不存在的情况

GET blog/_doc/2

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "2",
  "found" : false
}

found字段值为false表明查询的文档不存在。
2.3、判定文档是否存在

HEAD blog/_doc/1

200 - OK

3、更新文档

3.1、更改id为1的文档，删除了author，修改content字段。

PUT blog/_doc/1
{
  "title":"1、VMware Workstation虚拟机软件安装图解",
  "content":"下载得到VMware-workstation-full-15.0.2-10952284.exe可执行文件...",
  "url":"http://x.co/6nc81"
}

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 2,
  "result" : "updated",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 1,
  "_primary_term" : 1
}

_version更新为2

查看该文档

GET blog/_doc/1

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 2,
  "found" : true,
  "_source" : {
    "title" : "1、VMware Workstation虚拟机软件安装图解",
    "content" : "下载得到VMware-workstation-full-15.0.2-10952284.exe可执行文件...",
    "url" : "http://x.co/6nc81"
  }
}

3.2、添加文档时，防止覆盖已存在的文档，可以通过_create加以限制。

PUT blog/_doc/1/_create
{
  "title":"1、VMware Workstation虚拟机软件安装图解",
  "content":"下载得到VMware-workstation-full-15.0.2-10952284.exe可执行文件...",
  "url":"http://x.co/6nc81"
}

该文档已经存在，添加失败。

{
  "error": {
    "root_cause": [
      {
        "type": "version_conflict_engine_exception",
        "reason": "[_doc][1]: version conflict, document already exists (current version [2])",
        "index_uuid": "GqC2fSqPS06GRfTLmh1TLg",
        "shard": "1",
        "index": "blog"
      }
    ],
    "type": "version_conflict_engine_exception",
    "reason": "[_doc][1]: version conflict, document already exists (current version [2])",
    "index_uuid": "GqC2fSqPS06GRfTLmh1TLg",
    "shard": "1",
    "index": "blog"
  },
  "status": 409
}

3.3、更新文档的字段
通过脚本更新制定字段，其中ctx是脚本语言中的一个执行对象，先获取_source，再修改content字段

POST blog/_doc/1/_update
{
  "script": {
    "source": "ctx._source.content="从官网下载VMware-workstation，双击可执行文件进行安装...""  
  } 
}

 响应结果如下：

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 3,
  "result" : "updated",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 2,
  "_primary_term" : 1
}

再次获取文档GET blog/_doc/1，响应结果如下

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 3,
  "found" : true,
  "_source" : {
    "title" : "1、VMware Workstation虚拟机软件安装图解",
    "content" : "从官网下载VMware-workstation，双击可执行文件进行安装...",
    "url" : "http://x.co/6nc81"
  }
}

3.4、添加字段

POST blog/_doc/1/_update
{
  "script": {
    "source": "ctx._source.author="chengyuqiang""  
  } 
}

再次获取文档GET blog/_doc/1，响应结果如下

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 4,
  "found" : true,
  "_source" : {
    "title" : "1、VMware Workstation虚拟机软件安装图解",
    "content" : "从官网下载VMware-workstation，双击可执行文件进行安装...",
    "url" : "http://x.co/6nc81",
    "author" : "chengyuqiang"
  }
}

3.5、删除字段

POST blog/_doc/1/_update
{
  "script": {
    "source": "ctx._source.remove("url")"  
  } 
}

再次获取文档GET blog/_doc/1，响应结果如下

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 5,
  "found" : true,
  "_source" : {
    "title" : "1、VMware Workstation虚拟机软件安装图解",
    "content" : "从官网下载VMware-workstation，双击可执行文件进行安装...",
    "author" : "chengyuqiang"
  }
}

4、删除文档

DELETE blog/_doc/1

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 6,
  "result" : "deleted",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 6,
  "_primary_term" : 1
}

再次判定该文档是否存在，执行HEAD blog/_doc/1，响应结果404 - Not Found

5、批量操作

如果文档数量非常庞大，商业运维中都是海量数据，一个一个操作文档显然不合实际。幸运的是ElasticSearch提供了文档的批量操作机制。我们已经知道mget允许一次性检索多个文档，ElasticSearch提供了Bulk API，可以执行批量索引、批量删除、批量更新等操作，也就是说Bulk API允许使用在单个步骤中进行多次 create 、 index 、 update 或 delete 请求。

bulk 与其他的请求体格式稍有不同，bulk请求格式如下：

{ action: { metadata }}

{ request body        }

{ action: { metadata }}

{ request body        }

...

这种格式类似一个有效的单行 JSON 文档 流 ，它通过换行符( )连接到一起。注意两个要点：

• 每行一定要以换行符( )结尾， 包括最后一行 。这些换行符被用作一个标记，可以有效分隔行。
• 这些行不能包含未转义的换行符，因为他们将会对解析造成干扰。这意味着这个 JSON 不 能使用 pretty 参数打印。
• action/metadata 行指定 哪一个文档 做 什么操作 。metadata 应该 指定被索引、创建、更新或者删除的文档的 _index 、 _type 和 _id 。
• request body 行由文档的 _source 本身组成–文档包含的字段和值。它是 index 和 create 操作所必需的。

5.1、批量导入

POST /_bulk
{ "create": { "_index": "blog", "_type": "_doc", "_id": "1" }}
{ "title": "1、VMware Workstation虚拟机软件安装图解" ,"author":"chengyuqiang","content":"官网下载VMware-workstation，双击可执行文件进行安装" , "url":"http://x.co/6nc81" }
{ "create": { "_index": "blog", "_type": "_doc", "_id": "2" }}
{ "title":  "2、Linux服务器安装图解" ,"author":  "chengyuqiang" ,"content": "VMware模拟Linux服务器安装图解" , "url": "http://x.co/6nc82" }
{ "create": { "_index": "blog", "_type": "_doc", "_id": "3" }}
{ "title":  "3、Xshell 6 个人版安装与远程操作连接服务器" , "author": "chengyuqiang" ,"content": "Xshell 6 个人版安装与远程操作连接服务器..." , "url": "http://x.co/6nc84" }

这个 Elasticsearch 响应包含 items 数组， 这个数组的内容是以请求的顺序列出来的每个请求的结果。

{
  "took" : 132,
  "errors" : false,
  "items" : [
    {
      "create" : {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 7,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 7,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "create" : {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "2",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 8,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "create" : {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "3",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 0,
        "_primary_term" : 1,
        "status" : 201
      }
    }
  ]
}

5.2、批量操作，包括删除、更新、新增

POST /_bulk
{ "delete": { "_index": "blog", "_type": "_doc", "_id": "1" }}
{ "update": { "_index": "blog", "_type": "_doc", "_id": "3", "retry_on_conflict" : 3} }
{ "doc" : {"title" : "Xshell教程"} }
{ "index": { "_index": "blog", "_type": "_doc", "_id": "4" }}
{ "title": "4、CentOS 7.x基本设置" ,"author":"chengyuqiang","content":"CentOS 7.x基本设置","url":"http://x.co/6nc85" }
{ "create": { "_index": "blog", "_type": "_doc", "_id": "5" }}
{ "title": "5、图解Linux下JDK安装与环境变量配置","author":"chengyuqiang" ,"content": "图解JDK安装配置" , "url": "http://x.co/6nc86" }

在7.0版本中，retry_on_conflict参数取代了之前的_retry_on_conflict

{
  "took" : 125,
  "errors" : false,
  "items" : [
    {
      "delete" : {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 2,
        "result" : "deleted",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 3,
        "_primary_term" : 1,
        "status" : 200
      }
    },
    {
      "update" : {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "3",
        "_version" : 2,
        "result" : "updated",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 4,
        "_primary_term" : 1,
        "status" : 200
      }
    },
    {
      "index" : {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "4",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 1,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "create" : {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "5",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 5,
        "_primary_term" : 1,
        "status" : 201
      }
    }
  ]
}

6、批量获取

GET blog/_doc/_mget
{
    "ids" : ["1", "2","3"]
}

id为1的文档已经删除，所以没有搜索到

{
  "docs" : [
    {
      "_index" : "blog",
      "_type" : "_doc",
      "_id" : "1",
      "found" : false
    },
    {
      "_index" : "blog",
      "_type" : "_doc",
      "_id" : "2",
      "_version" : 1,
      "found" : true,
      "_source" : {
        "title" : "2、Linux服务器安装图解",
        "author" : "chengyuqiang",
        "content" : "VMware模拟Linux服务器安装图解",
        "url" : "http://x.co/6nc82"
      }
    },
    {
      "_index" : "blog",
      "_type" : "_doc",
      "_id" : "3",
      "_version" : 2,
      "found" : true,
      "_source" : {
        "title" : "Xshell教程",
        "author" : "chengyuqiang",
        "content" : "Xshell 6 个人版安装与远程操作连接服务器...",
        "url" : "http://x.co/6nc84"
      }
    }
  ]
}

7、简单搜索

这里介绍一下简单的文档搜索操作，后面章节会详细介绍。
7.1、词项查询， 也称term查询

GET blog/_search
{
  "query": {
    "term": {
      "title": "centos"
    }
  }
}

{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 2,
    "successful" : 2,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 0.71023846,
    "hits" : [
      {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "4",
        "_score" : 0.71023846,
        "_source" : {
          "title" : "4、CentOS 7.x基本设置",
          "author" : "chengyuqiang",
          "content" : "CentOS 7.x基本设置",
          "url" : "http://x.co/6nc85"
        }
      }
    ]
  }
}

GET blog/_search
{
  "query": {
    "term": {
      "title": "远程"
    }
  }
}

{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 2,
    "successful" : 2,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 0,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  }
}

GET blog/_search
{
  "query": {
    "term": {
      "title": "程"
    }
  }
}

{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 2,
    "successful" : 2,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.3486402,
    "hits" : [
      {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.3486402,
        "_source" : {
          "title" : "Xshell教程",
          "author" : "chengyuqiang",
          "content" : "Xshell 6 个人版安装与远程操作连接服务器...",
          "url" : "http://x.co/6nc84"
        }
      }
    ]
  }
}

7.2、匹配查询，也称match查询
与term精确查询不同，对于match查询，只要被查询字段中存在任何一个词项被匹配，就会搜索到该文档。

GET blog/_search
{
  "query": {
    "match": {
      "title": {
        "query": "远程"
      }
    }
  }
}

{
  "took" : 9,
  "timed_out" : false,
  "_shards" : {
    "total" : 2,
    "successful" : 2,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.3486402,
    "hits" : [
      {
        "_index" : "blog",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.3486402,
        "_source" : {
          "title" : "Xshell教程",
          "author" : "chengyuqiang",
          "content" : "Xshell 6 个人版安装与远程操作连接服务器...",
          "url" : "http://x.co/6nc84"
        }
      }
    ]
  }
}

8、路由机制

当你索引（动词，对该文档建立倒排索引）一个文档，它被存储到master节点上的一个主分片上。

Elasticsearch是如何知道文档属于哪个分片的呢？当你创建一个新文档，它是如何知道是应该存储在分片1还是分片2上的呢？
解答这个问题，我们需要了解Elasticsearch的路由机制。
简单地说，Elasticsearch将具有相关Hash值的文档存放到同一个主分片中，分片位置计算算法如下：

shard = hash(routing) % number_of_primary_shards

算法说明：

• routing值是一个字符串，它默认是文档_id，也可以自定义。这个routing字符串通过哈希函数生成一个数字，然后除以主切片的数量得到一个余数(remainder)，余数的范围是[0 , number_of_primary_shards-1]，这个数字就是特定文档所在的分片。
• 之前我们介绍过，创建索引时需要指定主分片数量，该不能修改。这是因为如果主分片的数量在未来改变了，所有先前的路由值就失效了，文档也就永远找不到了。
• 该算法基本可以保证所有文档在所有分片上平均分布，不会导致数据分布不均（数据倾斜）的情况。
• 默认情况下，routing值是文档的_id。我们创建文档时可以指定id的值；如果不指定id时，Elasticsearch将随机生成文档的_id值。这将导致在查询文档时，Elasticsearch不能确定文档的位置，需要将请求广播到所有的分片节点上。

假设我们有一个10个分片的索引。当一个请求在集群上执行时基本过程如下：

• 这个搜索的请求会被发送到一个节点。
• 接收到这个请求的节点，将这个查询广播到这个索引的每个分片上（可能是主分片，也可能是复制分片）。
• 每个分片执行这个搜索查询并返回结果。
• 结果在通道节点上合并、排序并返回给用户。

了解Elasticsearch的路由机制后，我们可以在创建某一类文档时指定文档的路由值，这样ElasticSearch就知道在处理这一类文档时，如何定位到正确的分片。比如，把某一特定类型的书籍存储到特定的分片上去，这样在搜索这一类书籍的时候就可以避免搜索其它的分片，也就避免了多个分片搜索结果的合并。路由机制向 Elasticsearch提供一种信息来决定哪些分片用于存储和查询。同一个路由值将映射到同一个分片。这基本上就是在说：“通过使用用户提供的路由值，就可以做到定向存储，定向搜索。

所有的文档API（GET、INDEX、DELETE、BULK、UPDATE、MGET）都接收一个routing参数，它用来自定义文档到分片的映射。添加routing参数形式与URL参数形式相同url?参数名=参数值。

PUT blog/_doc/1?routing=haron
{
  "title":"1、VMware安装",
  "author":"hadron",
  "content":"VMware Workstation虚拟机软件安装图解...",
  "url":"http://x.co/6nc81"
}

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 12,
  "_primary_term" : 1
}

GET blog/_doc/1?routing=hardon

{
  "_index" : "blog",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 1,
  "_routing" : "hardon",
  "found" : true,
  "_source" : {
    "title" : "1、VMware安装",
    "author" : "hadron",
    "content" : "VMware Workstation虚拟机软件安装图解...",
    "url" : "http://x.co/6nc81"
  }
}

注意：自定义routing值可以造成数据分布不均的情况。例如用户hadron的文档非常多，有数十万个，而其他大多数用户的文档只有数个到数十个，这样将导致hadron所在的分片较大。

9、版本控制

参考文档
https://www.elastic.co/guide/en/elasticsearch/guide/2.x/version-control.html
https://www.elastic.co/guide/en/elasticsearch/guide/2.x/optimistic-concurrency-control.html

https://elasticsearch.cn/book/elasticsearch_definitive_guide_2.x/version-control.html
https://elasticsearch.cn/book/elasticsearch_definitive_guide_2.x/optimistic-concurrency-control.html

PUT website
{
    "settings" : {
        "index" : {
            "number_of_shards" : 1,
            "number_of_replicas" : 1
        }
    }
}

PUT /website/_doc/1/_create
{
  "title": "My first blog entry",
  "text":  "Just trying this out..."
}

GET website/_doc/1

{
  "_index" : "website",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 1,
  "found" : true,
  "_source" : {
    "title" : "My first blog entry",
    "text" : "Just trying this out..."
  }
}

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

{
  "_index" : "website",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 2,
  "result" : "updated",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 1,
  "_primary_term" : 1
}

例如，要创建一个新的具有外部版本号 5 的博客文章，我们可以按以下方法进行：

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

在响应中，我们能看到当前的 _version 版本号是 5 ：

{
  "_index" : "website",
  "_type" : "_doc",
  "_id" : "2",
  "_version" : 5,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 2,
  "_primary_term" : 1
}

现在我们更新这个文档，指定一个新的 version 号是 10 ：

PUT /website/_doc/2?version=10&version_type=external
{
  "title": "My first external blog entry",
  "text":  "This is a piece of cake..."
}

请求成功并将当前 _version 设为 10 ：

{
  "_index" : "website",
  "_type" : "_doc",
  "_id" : "2",
  "_version" : 10,
  "result" : "updated",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 3,
  "_primary_term" : 1
}

如果你要重新运行此请求时，它将会失败，并返回像我们之前看到的同样的冲突错误， 因为指定的外部版本号不大于 Elasticsearch 的当前版本号。

{
  "error": {
    "root_cause": [
      {
        "type": "version_conflict_engine_exception",
        "reason": "[_doc][2]: version conflict, current version [10] is higher or equal to the one provided [10]",
        "index_uuid": "5616aEUkQ7yvQIYUDyLudg",
        "shard": "0",
        "index": "website"
      }
    ],
    "type": "version_conflict_engine_exception",
    "reason": "[_doc][2]: version conflict, current version [10] is higher or equal to the one provided [10]",
    "index_uuid": "5616aEUkQ7yvQIYUDyLudg",
    "shard": "0",
    "index": "website"
  },
  "status": 409
}

10、refresh

10.1、立即刷新，文档可见

这些将创建一个文档并立即刷新索引，使其可见：

DELETE test
PUT test/_doc/1?refresh
{"message": "测试文档1"}
PUT test/_doc/2?refresh=true
{"message": "测试文档2"}

10.2、不刷新

这些将创建一个文档而不做任何使搜索可见的内容：

PUT test/_doc/3
{"message": "测试文档3"}
PUT test/_doc/4?refresh=false
{"message": "测试文档4"}

10.3、等待刷新可见

PUT test/_doc/5?refresh=wait_for
{"message": "测试文档5"}