1. 集群管理API

es提供了一套api，叫做cat api，可以查看es集群中各种各样的数据

1.1 health（检查集群健康状况）

GET /_cat/health?v

epoch	timestamp	cluster	status	node.total	node.data shards	pri	relo	init	unassign	pending_tasks	max_task_wait_time	active_shards_percent
1591628823	15:12:21	myes	`green`	1	1	4	4	0	0	1	0	100.0%

1.2 集群的健康状况都有哪些？

green：每个索引的primary shard和replica shard都是active状态的
yellow：每个索引的primary shard都是active状态的，但是部分replica shard不是active状态，处于不可用的状态。
red：不是所有索引的primary shard都是active状态的，部分索引有数据丢失了

1.3 查看集群中有哪些索引

GET /_cat/indices?v

health	status	index	uuid	pri	docs.count	docs.deleted	store.size	pri.store.size
green	open	.apm-custom-link	DFglk9oCSoair5AXNm7HzA	1	0	0	208b	208b
green	open	.kibana_task_manager_1	88fMwSkJS6ul63ehKxAJgw	1	5	2	37.2kb	37.2kb
green	open	.apm-agent-configuration	Qk2cC8aYRkKqQ9FC_H69Bw	1	0	0	208b	208b
green	open	.kibana_1	1W6EX6-GSVy5Ije9ifFBdg	1	9	0	45.4kb	45.4kb

2. 索引操作

2.1 创建索引

PUT /test_index?pretty

由于index在创建时已经指定了固定数量的shard，shard的数量一旦指定了就不能扩展，如果用一个index来保存所有的数据，将会导致shard的数据越来越多，最终内存不足，需要频繁IO，ES性能会越来越慢。

创建索引的原则：

document结构相似的放在相同的index中。例如商品、商品详情这些document有很多相同的filed，可以放在同一index下。

document结构基本不同的存放在不同的index中。例如店铺、订单这些document基本不一样，不应该放在同一个index中

索引名称必须是小写的，不能用下划线开头，不能包含逗号

2.2 查看索引

GET /_cat/indices?v

health	status	index	uuid	pri	rep	docs.count	docs.deleted	store.size	pri.store.size
green	open	.apm-custom-link	DFglk9oCSoair5AXNm7HzA	1	0	0	0	208b	208b
green	open	.kibana_task_manager_1	88fMwSkJS6ul63ehKxAJgw	1	0	5	2	37.2kb	37.2kb
green	open	.apm-agent-configuration	Qk2cC8aYRkKqQ9FC_H69Bw	1	0	0	0	208b	208b
green	open	.kibana_1	1W6EX6-GSVy5Ije9ifFBdg	1	0	9	0	45.4kb	45.4kb
yellow	open	test_index	k32Hm22UQ3iwA0_PyU3Msw	1	1	0	0	208b	208b

为什么新创建的test_index是yellow呢？

因为默认创建的索引replica shard为1，就是说需要有另一个ES做数据备份，由于我这里只启动一台ES，replica没办法备份，所以就为yello，只需再启动一台ES就会自动把test_index同步过去。

2.3 删除索引

DELETE /test_index?pretty

查看索引验证是否还能被检索得到：

GET /_cat/indices?v

health	status	index	uuid	pri	docs.count	docs.deleted	store.size	pri.store.size
green	open	.apm-custom-link	DFglk9oCSoair5AXNm7HzA	1	0	0	208b	208b
green	open	.kibana_task_manager_1	88fMwSkJS6ul63ehKxAJgw	1	5	2	37.2kb	37.2kb
green	open	.apm-agent-configuration	Qk2cC8aYRkKqQ9FC_H69Bw	1	0	0	208b	208b
green	open	.kibana_1	1W6EX6-GSVy5Ije9ifFBdg	1	9	0	45.4kb	45.4kb

可以看到刚才创建的test_index被成功删除了

2.3 document的CRUD操作

2.3.1 创建文档（新增商品）

格式：

PUT /index/_doc/id
{
  "json数据"
}

我们可以手动指定document的id（格式：PUT /index/type/id），如果不指定es会自动创建一个id。

ES使用GUID自动生成id：

长度: 20个字符

URL安全(分布式系统并行生成时不会冲突)

base64编码

重复执行PUT操作会直接覆盖旧的数据

添加一些测试数据

PUT /goods/_doc/1
{
    "name" : "zhonghua yagao",
    "desc" :  "gaoxiao meibai",
    "price" :  18,
    "producer" :"zhonghua producer",
    "tags": [ "meibai", "fangzhu" ]
}

输出结果：

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

继续添加几条数据：

PUT /goods/_doc/2
{
    "name" : "jiajieshi yagao",
    "desc" :  "youxiao fangzhu",
    "price" :  25,
    "producer" :      "jiajieshi producer",
    "tags": [ "fangzhu" ]
}

PUT /goods/_doc/3
{
    "name" : "zhonghua yagao",
    "desc" :  "caoben zhiwu",
    "price" :  40,
    "producer" :      "zhonghua producer",
    "tags": [ "qingxin" ]
}

重点：

es会自动建立index和type，不需要提前创建

在插入document时，es默认会对document每个field都建立倒排索引，让其可以被搜索。

PS：ES 6.o+以后建议使用_doc名称的type，如果输入其他名称的type会出警告

#! Deprecation: [types removal] Specifying types in document index requests is deprecated, use the typeless endpoints instead (/{index}/_doc/{id}, /{index}/_doc, or /{index}/_create/{id}).

2.3.2 检索文档（_source返回全部fied）

语法

GET /index/_doc/id

GET /goods/_doc/1

输出：
{
  "_index" : "goods",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 2,
  "_seq_no" : 1,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "name" : "zhonghua yagao",
    "desc" : "gaoxiao meibai",
    "price" : 18,
    "producer" : "zhonghua producer",
    "tags" : [
      "meibai",
      "fangzhu"
    ]
  }
}

2.3.3 文档全量更新

PUT /goods/_doc/1
{
    "name" : "jiaqiangban gaolujie yagao",
    "desc" :  "gaoxiao meibai",
    "price" :  30,
    "producer" :      "gaolujie producer",
    "tags": [ "meibai", "fangzhu" ]
}

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

如果执行的是下面的语法，文档将会丢失desc、price、producer、tags字段

PUT /goods/_doc/1
{
    "name" : "jiaqiangban gaolujie yagao"
}

使用这种语法如果不希望其他字段丢失的话必须带上所有的field，才能去进行信息的修改

原理：

document是不可变的，这种方式属于全量替换

es会将老的document标记为deleted，标记为deleted的document将不能被检索到，此时老document并没有被物理删除

根据我们传过来的fied新增一个document，新document版本号会在老document的基础上+1

es会在适当的时机在后台物理删除标记为deleted的document

2.3.4 文档部分更新

这种方式叫：partial update部分更新

POST /goods/_doc/1_update
{
  "doc":{
    "name":"mei bai zhong hua ya gao"
  }
}
输出：
{
  "_index" : "goods",
  "_type" : "_doc",
  "_id" : "1_update",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 7,
  "_primary_term" : 1
}

使用POST /index/type/id_update语法来更新文档不需要把每个filed都带上，没带上的fied不会被删除

原理：

document是不可变的，这种方式属于部分替换

es先把老document的数据查询出来

然后将老的document标记为deleted，标记为deleted的document将不能被检索到，此时老document并没有被物理删除

新增一个document，根据我们传过来的fied在老的数据基础上进行数据替换，新document版本号会在老document的基础上+1

es会在适当的时机在后台物理删除标记为deleted的document

partial update的并发冲突问题：

POST /goods/_doc/1_update?retry_on_conflict=5 冲突时重试5次

根据官方文档描述，默认retry_on_conflict为0，发生冲突时会直接失败

2.3.5 删除文档

DELETE /goods/_doc/1
输出：
{
  "_index" : "goods",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 9,
  "result" : "deleted",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 11,
  "_primary_term" : 1
}

原理：

ES并不会直接删除这个document，只是将这个document标记为deleted

标记为deleted的document将不能被检索到，此时老document并没有被物理删除

es会在适当的时机在后台物理删除标记为deleted的document

GET /goods/_doc/1

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

2.3.6 检索文档（指定_source返回的fied）

GET /goods/_doc/1?_source=name,desc

{
  "_index" : "goods",
  "_type" : "_doc",
  "_id" : "1",
  "_version" : 4,
  "_seq_no" : 17,
  "_primary_term" : 5,
  "found" : true,
  "_source" : {
    "name" : "jiaqiangban gaolujie yagao",
    "desc" : "gaoxiao meibai"
  }
}

2.3.7 仅创建文档（如果文档已存在则报错）

PUT /goods/_doc/1?op_type=create
{
    "name" : "zhonghua yagao"
}

输出：
{
  "error" : {
    "root_cause" : [
      {
        "type" : "version_conflict_engine_exception",
        "reason" : "[1]: version conflict, document already exists (current version [4])",
        "index_uuid" : "_f8Bi42fTnymwg0vMsy4Kg",
        "shard" : "0",
        "index" : "goods"
      }
    ],
    "type" : "version_conflict_engine_exception",
    "reason" : "[1]: version conflict, document already exists (current version [4])",
    "index_uuid" : "_f8Bi42fTnymwg0vMsy4Kg",
    "shard" : "0",
    "index" : "goods"
  },
  "status" : 409
}

3. search API

3.1 query string search（字符串搜索）

传参方式：

请求行

query string search命名由来

因为search参数都是通过http请求的query string传过来的

适用场景

在命令行临时使用，比如curl快速发出请求，来检索想要的信息；对于复杂的查询，是很难去构建的因此在生产环境中，几乎很少使用query string search

3.1.1 搜索全部

GET /goods/_search
输出：
{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 3,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "name" : "jiajieshi yagao",
          "desc" : "youxiao fangzhu",
          "price" : 25,
          "producer" : "jiajieshi producer",
          "tags" : [
            "fangzhu"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.0,
        "_source" : {
          "name" : "zhonghua yagao",
          "desc" : "caoben zhiwu",
          "price" : 40,
          "producer" : "zhonghua producer",
          "tags" : [
            "qingxin"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "1_update",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "name" : "mei bai zhong hua ya gao"
          }
        }
      }
    ]
  }
}

took：耗费了几毫秒（为0的话表示缓存中有完整数据）
timed_out：是否超时，这里是没有
_shards：数据拆成了几个分片，所以对于搜索请求，会打到所有的primary - shard（或者是它的某个replica shard也可以）
hits.total：查询结果包含多少条document
hits.max_score：score的含义，就是document对于一个search的相关度的匹配分数，相关度越高分数越高
hits.hits：匹配的document的详细数据

3.1.2 根据条件搜索

搜索商品名称中包含yagao的商品，而且按照售价降序排序：

GET /goods/_search?q=name:yagao&sort=price:desc

输出：
{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : null,
        "_source" : {
          "name" : "zhonghua yagao",
          "desc" : "caoben zhiwu",
          "price" : 40,
          "producer" : "zhonghua producer",
          "tags" : [
            "qingxin"
          ]
        },
        "sort" : [
          40
        ]
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : null,
        "_source" : {
          "name" : "jiajieshi yagao",
          "desc" : "youxiao fangzhu",
          "price" : 25,
          "producer" : "jiajieshi producer",
          "tags" : [
            "fangzhu"
          ]
        },
        "sort" : [
          25
        ]
      }
    ]
  }
}

3.1.3 包含与不包含

包含

GET /goods/_search?q=+name:yagao

name这个fied必须包含yagao才会返回 2. 不包含

GET /goods/_search?q=-name:yagao

name这个fied必须不包含yagao才会返回

3.2 query DSL（特定领域语言）

传参方式：

请求体

DSL含义

Domain Specified Language，特定领域的语言

DSL特点

以json格式构建查询语法，可以轻易构建各种复杂的语法，比query string search强大多了

3.2.1 查询所有

GET /goods/_search { "query": {"match_all": {}} }

3.2.2 简单条件查询

查询名称包含yagao的商品，同时按照价格降序排序

GET /goods/_search
{
  "query": {"match": {
    "name": "yagao"
  }},
  "sort": [
    {
      "price": "desc"
    }
  ]
}

分页查询商品，总共3条商品，每页显示2条商品，显示第2页

GET /goods/_search
{
  "query": {"match_all": {}}
  , "from": 1,
  "size": 2
}

指定要查询出来商品的名称和价格

GET /goods/_search
{
  "query": {"match_all": {}},
  "_source": ["name","price"]
}

3.2.3 query、filter

搜索商品名称包含yagao，而且售价大于25元的商品

GET /goods/_search { "query": { "bool": { "must": { "match":{ "name":"yagao" } }, "filter": { "range": { "price": {"gt": 25} } } } } }

filter与query对比

filter：仅仅只是按照搜索条件过滤出需要的数据而已，不计算任何相关度分数，对相关度没有任何影响

query，会去计算每个document相对于搜索条件的相关度，并按照相关度进行排序

如果搜索需要将最匹配搜索条件的数据先返回，那么用query；如果只是要根据条件筛选出一部分数据，不关注其排序，那么用filter

filter与query性能

filter：不需要计算相关度分数，不需要按照相关度分数进行排序，同时还有内置cache自动缓存最常使用filter的数据

query：相反，要计算相关度分数，按照分数进行排序，而且无法cache结果

3.2.4 full-text search（全文检索）

自带分词功能全文检索，返回根据根据_score排序

添加一条商品

PUT /goods/_doc/4
{
  "name":"special yagao",
  "desc":"special meibai",
  "price":50,
  "producer":"special yagao producer",
  "tags":["meibai"]
}

全文检索

GET /goods/_search
{
"query": {
    "match": {
      "name": "zhonghua yagao"
    }
  }
}

输出：
{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 4,
      "relation" : "eq"
    },
    "max_score" : 1.3716825,
    "hits" : [
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.3716825,
        "_source" : {
          "name" : "zhonghua yagao",
          "desc" : "caoben zhiwu",
          "price" : 40,
          "producer" : "zhonghua producer",
          "tags" : [
            "qingxin"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 0.110377684,
        "_source" : {
          "name" : "jiajieshi yagao",
          "desc" : "youxiao fangzhu",
          "price" : 25,
          "producer" : "jiajieshi producer",
          "tags" : [
            "fangzhu"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "4",
        "_score" : 0.110377684,
        "_source" : {
          "name" : "special yagao",
          "desc" : "special meibai",
          "price" : 50,
          "producer" : "special yagao producer",
          "tags" : [
            "meibai"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 0.09271726,
        "_source" : {
          "name" : "jiaqiangban gaolujie yagao",
          "desc" : "gaoxiao meibai",
          "price" : 30,
          "producer" : "gaolujie producer",
          "tags" : [
            "meibai",
            "fangzhu"
          ]
        }
      }
    ]
  }
}

3.2.5 phrase search（短语搜索）

phrase search与full text search的区别

full text search：将搜索关键字分词，去倒排索引里匹配，只要能匹配上任意一个拆解后的单词，就会把这条document返回。
phrase search：搜索关键字必须与filed完全匹配，才会把这条document返回

GET /goods/_search
{
"query": {
    "match": {
      "name": "zhonghua yagao"
    }
  }
}
输出：
{
  "took" : 8,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.3716825,
    "hits" : [
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.3716825,
        "_source" : {
          "name" : "zhonghua yagao",
          "desc" : "caoben zhiwu",
          "price" : 40,
          "producer" : "zhonghua producer",
          "tags" : [
            "qingxin"
          ]
        }
      }
    ]
  }
}

3.2.6 highlight search（高亮搜索结果）

GET /goods/_search
{
"query": {
    "match": {
      "name": "zhonghua yagao"
    }
  },
  "highlight": {
    "fields": {
      "name": {}
    }
  }
}

输出：
{
  "took" : 34,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 4,
      "relation" : "eq"
    },
    "max_score" : 1.3716825,
    "hits" : [
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.3716825,
        "_source" : {
          "name" : "zhonghua yagao",
          "desc" : "caoben zhiwu",
          "price" : 40,
          "producer" : "zhonghua producer",
          "tags" : [
            "qingxin"
          ]
        },
        "highlight" : {
          "name" : [
            "<em>zhonghua</em> <em>yagao</em>"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 0.110377684,
        "_source" : {
          "name" : "jiajieshi yagao",
          "desc" : "youxiao fangzhu",
          "price" : 25,
          "producer" : "jiajieshi producer",
          "tags" : [
            "fangzhu"
          ]
        },
        "highlight" : {
          "name" : [
            "jiajieshi <em>yagao</em>"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "4",
        "_score" : 0.110377684,
        "_source" : {
          "name" : "special yagao",
          "desc" : "special meibai",
          "price" : 50,
          "producer" : "special yagao producer",
          "tags" : [
            "meibai"
          ]
        },
        "highlight" : {
          "name" : [
            "special <em>yagao</em>"
          ]
        }
      },
      {
        "_index" : "goods",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 0.09271726,
        "_source" : {
          "name" : "jiaqiangban gaolujie yagao",
          "desc" : "gaoxiao meibai",
          "price" : 30,
          "producer" : "gaolujie producer",
          "tags" : [
            "meibai",
            "fangzhu"
          ]
        },
        "highlight" : {
          "name" : [
            "jiaqiangban gaolujie <em>yagao</em>"
          ]
        }
      }
    ]
  }
}

可以看到yagao和zhonghua关键字旁边带上了<em>标签

3.2.7 agg（数据统计）

计算每个tags下的商品数量

GET /goods/_search
{
  "size": 0, 
  "aggs": {
    "group_by_tags": {
      "terms": {
        "field": "tags"
      }
    }
  }
}

报错

"Text fields are not optimised for operations that require per-document field data like aggregations and sorting, so these operations are disabled by default. Please use a keyword field instead. Alternatively, set fielddata=true on [tags] in order to load field data by uninverting the inverted index. Note that this can use significant memory." 解决办法：将tags的field的fielddata属性设置为true，即建立正排索引

PUT /goods/_mapping
{
  "properties":{
    "tags":{
      "type":"text",
      "fielddata":true
    }
  }
}

继续执行上面的统计tags请求

输出：
{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 5,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  },
  "aggregations" : {
    "group_by_tags" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "fangzhu",
          "doc_count" : 2
        },
        {
          "key" : "meibai",
          "doc_count" : 2
        },
        {
          "key" : "qingxin",
          "doc_count" : 1
        }
      ]
    }
  }
}

buckets：分组的结果 buckets.key：组名 buckets.doc_count：组名对应的document数量

名称中包含yagao的商品，计算每个tag下的商品数量

GET /goods/_search
{
  "size": 0, 
  "query": {
    "match": {
      "name": "yagao"
    }
  }, 
  "aggs": {
    "group_by_tags": {
      "terms": {
        "field": "tags"
      }
    }
  }
}

根据tags分组，再算每组平均价格,根据平均价格降序排序

GET /goods/_search
{
  "size": 0, 
  "aggs": {
    "group_by_tags": {
      "terms": {
        "field": "tags",
        "order": {
          "avg_price": "desc"
        }
      },
      "aggs": {
        "avg_price": {
          "avg": {
            "field": "price"
          }
        }
      }
    }
  }
}
输出：
{
  "took" : 3,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 5,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  },
  "aggregations" : {
    "group_by_tags" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "meibai",
          "doc_count" : 2,
          "avg_price" : {
            "value" : 40.0
          }
        },
        {
          "key" : "qingxin",
          "doc_count" : 1,
          "avg_price" : {
            "value" : 40.0
          }
        },
        {
          "key" : "fangzhu",
          "doc_count" : 2,
          "avg_price" : {
            "value" : 27.5
          }
        }
      ]
    }
  }
}

按照指定的价格范围区间进行分组，然后在每组内再按照tag进行分组，最后再计算每组的平均价格

GET /goods/_search
{
  "size": 0, 
  "aggs": {
    "group_by_price": {
      "range": {
        "field": "price",
        "ranges": [
          {
            "from": 0,
            "to":20
          },
          {
            "from": 20,
            "to":40
          }
        ]
      },
      "aggs": {
        "group_by_tags": {
          "terms": {
            "field": "tags"
          }
          , "aggs": {
            "average_price": {
              "avg": {
                "field": "price"
              }
            }
          }
        }
      }
    }
  }
}

ES入门篇5--语法与原理

1. 集群管理API

1.1 health（检查集群健康状况）

1.2 集群的健康状况都有哪些？

1.3 查看集群中有哪些索引

2. 索引操作

2.1 创建索引

2.2 查看索引

2.3 删除索引

2.3 document的CRUD操作

2.3.1 创建文档（新增商品）

2.3.2 检索文档（_source返回全部fied）

2.3.3 文档全量更新

2.3.4 文档部分更新

2.3.5 删除文档

2.3.6 检索文档（指定_source返回的fied）

2.3.7 仅创建文档（如果文档已存在则报错）

3. search API

3.1 query string search（字符串搜索）

3.1.1 搜索全部

3.1.2 根据条件搜索

3.1.3 包含与不包含

3.2 query DSL（特定领域语言）

3.2.1 查询所有

3.2.2 简单条件查询

3.2.3 query、filter

3.2.4 full-text search（全文检索）

3.2.5 phrase search（短语搜索）

3.2.6 highlight search（高亮搜索结果）

3.2.7 agg（数据统计）