ElasticSearch（二）：文档的基本CRUD与批量操作

ElasticSearch（二）：文档的基本CRUD与批量操作

学习课程链接《Elasticsearch核心技术与实战》

## Create 文档
支持自动生成文档_id和指定文档_id两种方式。
* 通过调用`POST index_name/_doc`，系统会自动生成文档 _id。
```
#create document. 自动生成 _id
POST users/_doc
{
"user" : "Mike",
"post_date" : "2019-04-15T14:12:12",
"message" : "trying out Kibana"
}
```
```
#返回结果
{
"_index" : "users",
"_type" : "_doc",
"_id" : "TyPHr20BkakgvNgYZu2L",#自动生成文档的_id
"_version" : 1,
"result" : "created",
"_shards" : {
"total" : 2,
"successful" : 1,
"failed" : 0
},
"_seq_no" : 1,
"_primary_term" : 1
}
```
* 使用`PUT index_name/_create/_id`或`PUT index_name/_doc/_id?op_type=create`创建时，URI中显示指定`_create`，此时如果该_id的文档已经存在，操作会失败。
```
#1.create document. 指定 _id 如果已经存在，就报错
PUT users/_create/1
{
"user" : "Jack",
"post_date" : "2019-05-15T14:12:12",
"message" : "trying out Elasticsearch"
}
#2.create document. 指定_id。如果_id已经存在，报错
PUT users/_doc/1?op_type=create
{
"user" : "Jack",
"post_date" : "2019-05-15T14:12:12",
"message" : "trying out Elasticsearch"
}
```
```
#如果_id已经存在报错信息，如下：
{
"error": {
"root_cause": [
{
"type": "version_conflict_engine_exception",
"reason": "[1]: version conflict, document already exists (current version [1])",
"index_uuid": "ohLNyzUmTv6cm-Ih9kH0bw",
"shard": "0",
"index": "users"
}
],
"type": "version_conflict_engine_exception",
"reason": "[1]: version conflict, document already exists (current version [1])",
"index_uuid": "ohLNyzUmTv6cm-Ih9kH0bw",
"shard": "0",
"index": "users"
},
"status": 409
}
```

## Index 文档
Index和Create不一样的地方：如果文档不存在，就索引新的文档。否则现有的文档会被删除，新的文档被索引，版本信息+1。使用`PUT index_name/_doc/_id`。
```
PUT users/_doc/1
{
"user" : "Mike"
}
```
```
#返回结果
{
"_index" : "users",
"_type" : "_doc",
"_id" : "1",
"_version" : 3, #版本增加
"result" : "updated",
"_shards" : {
"total" : 2,
"successful" : 1,
"failed" : 0
},
"_seq_no" : 4,
"_primary_term" : 2
}
```

## Update 文档
Update方法不会删除原来的文档，而是实现真正的数据更新，更新的文档必须存在，更新的内容需要包含在`doc`中。
```
#更新文档API
POST index_name/_update/_id
{
"doc":{
"field1":"value1",
"field2":"value2"
}
}
```

 #更新_id=1文档
POST users/_update/1
{
    "doc":{
        "post_date" : "2019-05-15T14:12:12",
         "message" : "trying out Elasticsearch"
    }
}

## Get 文档
根据文档ID，获取相应文档信息，`GET index_name/_doc/_id`
```
#Get the document by ID
GET users/_doc/1
```
```
#返回结果
{
"_index" : "users",
"_type" : "_doc",
"_id" : "1",
"_version" : 1,
"_seq_no" : 2,
"_primary_term" : 1,
"found" : true,
"_source" : {
"user" : "Jack",
"post_date" : "2019-05-15T14:12:12",
"message" : "trying out Elasticsearch"
}
}
```

## Delete 文档
根据文档ID，删除相应文档信息，`DELETE index_name/_doc/_id`
```
# 删除文档
DELETE users/_doc/1
```

## 批量操作-bulk
批量操作，可以减少网络连接所产生的开销，提高性能。
* 支持在一次API调用中，对不同的索引进行操作。
* 支持四种类型操作：`Index`,`Create`,`Update`,`Delete`。
* 可以在URI中指定Index，也可以在请求中指定。
* 操作中单条操作失败，并不会影响其他操作。
* 返回结果包括了每一条操作执行的结果。
* 不要发送过多数据，一般建议是1000-5000个文档，如果你的文档很大，可以适当减少队列，大小建议是5-15MB，默认不能超过100M，会报错。

### Bulk 操作
POST _bulk
{ "index" : { "_index" : "test", "_id" : "1" } }
{ "field1" : "value1" }
{ "delete" : { "_index" : "test", "_id" : "2" } }
{ "create" : { "_index" : "test2", "_id" : "3" } }
{ "field1" : "value3" }
{ "update" : {"_id" : "1", "_index" : "test"} }
{ "doc" : {"field2" : "value2"} }

#返回结果
{
  "took" : 227,
  "errors" : false,
  "items" : [
    {
      "index" : {
        "_index" : "test",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 0,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "delete" : {
        "_index" : "test",
        "_type" : "_doc",
        "_id" : "2",
        "_version" : 1,
        "result" : "not_found",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 1,
        "_primary_term" : 1,
        "status" : 404
      }
    },
    {
      "create" : {
        "_index" : "test2",
        "_type" : "_doc",
        "_id" : "3",
        "_version" : 1,
        "result" : "created",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 0,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "update" : {
        "_index" : "test",
        "_type" : "_doc",
        "_id" : "1",
        "_version" : 2,
        "result" : "updated",
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 2,
        "_primary_term" : 1,
        "status" : 200
      }
    }
  ]
}

## 批量读取-mget
mget 是通过文档`_id`列表得到文档信息。
```
### mget 操作
GET /_mget
{
"docs" : [
{
"_index" : "test",
"_id" : "1"
},
{
"_index" : "test",
"_id" : "2"
}
]
}

URI中指定index

GET /test/_mget

{

"docs" : [

{

"_id" : "1"

},

{

"_id" : "2"

}

]

}

GET /_mget

{

"docs" : [

{

"_index" : "test",

"_id" : "1",

"_source" : false

},

{

"_index" : "test",

"_id" : "2",

"_source" : ["field3", "field4"]

},

{

"_index" : "test",

"_id" : "3",

"_source" : {

"include": ["user"],

"exclude": ["user.location"]

}

}

]

}

返回结果

{

"docs" : [

{

"_index" : "test",

"_type" : "_doc",

"_id" : "1",

"_version" : 4,

"_seq_no" : 5,

"_primary_term" : 1,

"found" : true,

"_source" : {

"field1" : "value1",

"field2" : "value2"

}

},

{

"_index" : "test",

"_type" : "_doc",

"_id" : "2",

"found" : false

}

]

}

<br/>
## 批量查询-msearch
msearch 是根据查询条件，搜索到相应文档。

POST kibana_sample_data_ecommerce/_msearch

{}

{"query" : {"match_all" : {}},"size":1}

{"index" : "kibana_sample_data_flights"}

{"query" : {"match_all" : {}},"size":2}

<br/>
## 常见错误返回说明
问题|原因
---|:--
无法连接|网络故障或集群挂了
连接无法关闭|网络故障或节点出错
429|集群过于繁忙
4xx|请求体格式有错
500|集群内部错误