Elasticsearch学习笔记之文档的增删改查

Elasticsearch相关概念讲解，参看官方博客 ，可以看下这篇文章对Elasticsearch来个初步印象：《终于有人把Elasticsearch原理讲透了》。

笔记参考：

官方博客：开始使用Elasticsearch (1)

假设我们已经安装好Elasticsearch和Kibana,浏览器输入ip:5601，进入Kibana操作界面，这次我们使用到的是Kibana菜单里的Dev Tools功能。

创建文档

执行如下命令：

POST twitter/_doc/1
{
    "username":"Dannis",
    "uid":1
}

这行命令表明，向Elasticsearch发送一个POST请求，创建一个名为twitter的索引（index），同时生成一个文档，文档的ID为1，点击三角图标执行请求。

生成结果为：

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

我们来分析下返回的结果信息，_index表明我们创建的索引名为twitter，_type类型是文档类型_doc，_id文档ID为1，这些信息都是我们在请求里指定的，没问题，接下来，version表示版本号，result表明我们的操作属于创建created，_shards表示分片信息，里面的信息表明有2个分片，成功1个，失败0个，这是什么意思呢？

我们执行GET _cat/shards/twitter命令，该命令是用来查看索引的分片信息，输出结果如下所示：

twitter 0 p STARTED    1 3.8kb 172.29.0.2 09baeea2d96a
twitter 0 r UNASSIGNED     

我们看到创建的索引twitter有两个分片，p是primary的首字母缩写，表示主分片，STAARTED表示分片正常。r又是什么呢？

我们再来看下索引的设置信息setting，输入并执行：

GET twitter/_settings

返回结果如下：

{
  "twitter" : {
    "settings" : {
      "index" : {
        "creation_date" : "1591930378288",
        "number_of_shards" : "1",
        "number_of_replicas" : "1",
        "uuid" : "3vc_AZQcQbGM-a6FtTSX5g",
        "version" : {
          "created" : "7070199"
        },
        "provided_name" : "twitter"
      }
    }
  }
}

可以看到索引的详细信息，creation_date表示索引的创建时间，以时间戳形式展示；number_of_shards表示主分片的数量，默认是1，number_of_replicas表示索引的副本数量，默认也是1。

回到上面GET _cat/shards/twitter命令的返回结果，我们知道了r 表示的是分片副本的意思，即replica的首字母，UNASSIGNED意为未分配，为什么是这个呢？这是因为我本地环境开启的的Elasticsearch环境为开发模式，只有一个节点，也就是主节点，如果开启的是集群模式，则副本数据则会自动分配到加入的节点上。

创建文档的时候，如果没有指定文档ID，Elasticsearch会自动给该文档生成一个ID，如下：

POST twitter/_doc
{
  "username":"test",
  "age":20
}

返回结果：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "EIcep3IBFDGGZnEIs9aT",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 4,
  "_primary_term" : 1
}

我们看到返回有将文档_id返回，再来查看一下：

GET twitter/_doc/EIcep3IBFDGGZnEIs9aT

返回内容正是我们期望写入的数据：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "EIcep3IBFDGGZnEIs9aT",
  "_version" : 1,
  "_seq_no" : 4,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "username" : "test",
    "age" : 20
  }
}

我们还可以通过调用_create方法来创建文档，如下：

POST twitter/_create/2
{
  "username":"GB",
  "uid":1,
  "city":"Guangzhou",
  "province":"Guangdong",
  "country":"China"
}

返回结果：

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

可知数据已成功写入，如果我们再次调用如下命令:

POST twitter/_create/2
{
  "username":"GB",
  "uid":1,
  "city":"Guangzhou",
  "province":"Guangdong",
  "country":"China"
}

返回结果如下：

{
  "error" : {
    "root_cause" : [
      {
        "type" : "version_conflict_engine_exception",
        "reason" : "[2]: version conflict, document already exists (current version [1])",
        "index_uuid" : "AiRNBupCRWWLFKqFSVW3mw",
        "shard" : "0",
        "index" : "twitter"
      }
    ],
    "type" : "version_conflict_engine_exception",
    "reason" : "[2]: version conflict, document already exists (current version [1])",
    "index_uuid" : "AiRNBupCRWWLFKqFSVW3mw",
    "shard" : "0",
    "index" : "twitter"
  },
  "status" : 409
}

返回错误，提示我们文档已经存在，那么如果执行下面的命令呢？

POST twitter/_doc/1
{
  "username":"Dannis",
  "uid":1
}

返回结果如下：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 2,
  "result" : "updated",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 7,
  "_primary_term" : 1
}

发现成功响应，只是result值变成了updated,并且版本号也变成了2，由此可知，如果使用POST twitter/_create/2方式来创建文档，只有该文档ID不存在才能创建成功，使用POST twitter/_doc/1方式来创建文档，如果文档不存在，则创建，如果文档已存在，则结果会变成对指定文档的更新操作，并且版本号加1。

查询文档

输入执行：

GET twitter/_doc/1

返回结果：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 1,
  "_seq_no" : 0,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "username" : "Dannis",
    "uid" : 1
  }
}

可以看到我们定义的文档数据被放在了_source字段下面，found字段表示查到了该文档，如果我们输入以下命令：

GET twitter/_doc/2

返回结果:

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

可以看到found为false。

修改文档

输入命令并执行：

POST twitter/_update/1
{
  "doc": {
    "username":"Dannis-update"
  }
}

返回结果：

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

我们看到result值变成了updated，_version也变成了2，再查看一下：

GET twitter/_doc/1

返回结果：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 2,
  "_seq_no" : 1,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "username" : "Dannis-update",
    "uid" : 1
  }
}

没问题，username已变成了我们想要的。

如果我们更新的时候是加入一个不存在的字段，看下发生什么？输入以下命令并执行：

POST twitter/_update/1
{
  "doc": {
    "age":25
  }
}

返回结果：

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

可以看到文档的版本号变为3了。

再来查看一下，

GET twitter/_doc/1

返回结果：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 3,
  "_seq_no" : 2,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "username" : "Dannis-update",
    "uid" : 1,
    "age" : 25
  }
}

发现返回的_source里也包含了刚加的内容，由此可知，如果字段存在，则会更新原来的字段内容，如果字段不存在，则会添加新的字段内容。

删除文档

输入命令并执行：

DELETE twitter/_doc/1

返回结果：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 4,
  "result" : "deleted",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 3,
  "_primary_term" : 1
}

可看到_version变成了4，而result为deleted，由此发现，我们对文档每进行一次写入/更新操作，版本号都会加1。

我们再来查看一下：

GET twitter/_doc/1

返回结果：

{
  "_index" : "twitter",
  "_type" : "_doc",
  "_id" : "1",
  "found" : false
}

found为false，表示找不到ID为1的文档了，表明删除文档成功。

下面来看下对文档的批量操作。

批量创建文档

批量创建多个文档，输入以下命令并执行：

POST _bulk
{"index":{"_index":"twitter","_id":3}}
{"username":"张三","uid":3,"age":30}
{"index":{"_index":"twitter","_id":4}}
{"username":"李四","uid":4,"age":25}
{"index":{"_index":"twitter","_id":5}}
{"username":"王五","uid":5,"age":18}

返回结果：

{
  "took" : 44,
  "errors" : false,
  "items" : [
    {
      "index" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "3",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 9,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "index" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "4",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 10,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "index" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "5",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 11,
        "_primary_term" : 1,
        "status" : 201
      }
    }
  ]
}

没有异常，如果我们想同时往不同的索引里写入数据呢？执行以下命令：

POST _bulk
{"index":{"_index":"twitter","_id":6}}
{"username":"Jack","uid":6,"age":22}
{"index":{"_index":"twitter_v1","_id":1}}
{"username":"test","age":20}

我们同时往twitter和twitter_v1各写入一条数据，分别用GET twitter/_doc/6和GET twitter_v1/_doc/1查询，都能正常查询到。

批量查询文档

如果我们想同时查询多个文档，可执行如下命令：

GET _mget
{
  "docs":[
    {
      "_index":"twitter",
      "_id":1
    },
    {
      "_index":"twitter",
      "_id":2
    }
  ]
}

返回结果：

{
  "docs" : [
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "1",
      "_version" : 3,
      "_seq_no" : 8,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "GB",
        "uid" : 1,
        "city" : "Guangzhou2",
        "province" : "Guangdong",
        "country" : "China"
      }
    },
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "2",
      "_version" : 1,
      "_seq_no" : 6,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "GB",
        "uid" : 1,
        "city" : "Guangzhou",
        "province" : "Guangdong",
        "country" : "China"
      }
    }
  ]
}

这是同时查同一个索引的文档，也可以同时查多个索引下的文档，比如：

GET _mget
{
  "docs":[
    {
      "_index":"twitter",
      "_id":1
    },
    {
      "_index":"twitter_v1",
      "_id":1
    }
  ]
}

结果如下：

{
  "docs" : [
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "1",
      "_version" : 3,
      "_seq_no" : 8,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "GB",
        "uid" : 1,
        "city" : "Guangzhou2",
        "province" : "Guangdong",
        "country" : "China"
      }
    },
    {
      "_index" : "twitter_v1",
      "_type" : "_doc",
      "_id" : "1",
      "_version" : 1,
      "_seq_no" : 0,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "test",
        "age" : 20
      }
    }
  ]
}

批量更新文档

批量更新文档，执行如下命令：

POST _bulk
{"update":{"_index":"twitter","_id":1}}
{"doc":{"username":"GB-update"}}
{"update":{"_index":"twitter_v1","_id":1}}
{"doc":{"age":25}}

返回结果：

{
  "took" : 107,
  "errors" : false,
  "items" : [
    {
      "update" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 4,
        "result" : "updated",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 13,
        "_primary_term" : 1,
        "status" : 200
      }
    },
    {
      "update" : {
        "_index" : "twitter_v1",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 2,
        "result" : "updated",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 1,
        "_primary_term" : 1,
        "status" : 200
      }
    }
  ]
}

我们再用以下命令查询一下：

GET _mget
{
  "docs":[
    {
      "_index":"twitter",
      "_id":1
    },
    {
      "_index":"twitter_v1",
      "_id":1
    }
  ]
}

返回结果如下所示，发现数据都变成了我们想要的内容。

{
  "docs" : [
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "1",
      "_version" : 4,
      "_seq_no" : 13,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "GB-update",
        "uid" : 1,
        "city" : "Guangzhou2",
        "province" : "Guangdong",
        "country" : "China"
      }
    },
    {
      "_index" : "twitter_v1",
      "_type" : "_doc",
      "_id" : "1",
      "_version" : 2,
      "_seq_no" : 1,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "test",
        "age" : 25
      }
    }
  ]
}

批量删除文档

批量删除文档跟批量更新的命令类似，如下：

POST _bulk
{"delete":{"_index":"twitter","_id":1}}
{"delete":{"_index":"twitter_v1","_id":1}}

返回结果：

{
  "took" : 80,
  "errors" : false,
  "items" : [
    {
      "delete" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 5,
        "result" : "deleted",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 14,
        "_primary_term" : 1,
        "status" : 200
      }
    },
    {
      "delete" : {
        "_index" : "twitter_v1",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 3,
        "result" : "deleted",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 2,
        "_primary_term" : 1,
        "status" : 200
      }
    }
  ]
}

我们再用GET _mget命令去查这两个文档的时候，发现是找不到数据了，返回结果如下：

{
  "docs" : [
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "1",
      "found" : false
    },
    {
      "_index" : "twitter_v1",
      "_type" : "_doc",
      "_id" : "1",
      "found" : false
    }
  ]
}

同时进行创建、更新、删除文档操作

通过上面的例子我们发现，对文档的批量操作都是通过_bulk命令来操作，只是传入的参数不同，那么可不可以同时进行创建、更新、删除操作呢？试一下：

POST _bulk
{"index":{"_index":"twitter","_id":10}}
{"username":"小飞飞","age":12}
{"update":{"_index":"twitter","_id":3}}
{"doc":{"username":"张三-update"}}
{"delete":{"_index":"twitter","_id":6}}

返回结果：

{
  "took" : 51,
  "errors" : false,
  "items" : [
    {
      "index" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "10",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 15,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "update" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "3",
        "_version" : 2,
        "result" : "updated",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 16,
        "_primary_term" : 1,
        "status" : 200
      }
    },
    {
      "delete" : {
        "_index" : "twitter",
        "_type" : "_doc",
        "_id" : "6",
        "_version" : 2,
        "result" : "deleted",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 17,
        "_primary_term" : 1,
        "status" : 200
      }
    }
  ]
}

我们再来批量查询一下：

GET _mget
{
  "docs":[
    {
      "_index":"twitter",
      "_id":10
    },
    {
      "_index":"twitter",
      "_id":3
    },
    {
      "_index":"twitter",
      "_id":6
    }
  ]
}

返回结果：

{
  "docs" : [
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "10",
      "_version" : 1,
      "_seq_no" : 15,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "小飞飞",
        "age" : 12
      }
    },
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "3",
      "_version" : 2,
      "_seq_no" : 16,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "张三-update",
        "uid" : 3,
        "age" : 30
      }
    },
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "6",
      "found" : false
    }
  ]
}

发现数据都符合预期。

到这里，发现了通过bulk创建文档时，参数：{"index":{"_index":"twitter","_id":10}}里的index其实是个动词，即创建索引，特此说明。

x":“twitter”,
“_id”:10
},
{
“_index”:“twitter”,
“_id”:3
},
{
“_index”:“twitter”,
“_id”:6
}
]
}

返回结果：

```json
{
  "docs" : [
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "10",
      "_version" : 1,
      "_seq_no" : 15,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "小飞飞",
        "age" : 12
      }
    },
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "3",
      "_version" : 2,
      "_seq_no" : 16,
      "_primary_term" : 1,
      "found" : true,
      "_source" : {
        "username" : "张三-update",
        "uid" : 3,
        "age" : 30
      }
    },
    {
      "_index" : "twitter",
      "_type" : "_doc",
      "_id" : "6",
      "found" : false
    }
  ]
}

发现数据都符合预期。

到这里，发现了通过bulk创建文档时，参数：{"index":{"_index":"twitter","_id":10}}里的index其实是个动词，即创建索引，特此说明。