title: "Elasticsearch学习笔记之文档的增删改查"
date: 2020-06-10T14:16:17+08:00
summary: "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，如图示：
dev-tools
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：
post-twitter-1
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。