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REST 指的是一组架构约束条件和原则。满足这些约束条件和原则的应用程序或设计就是RESTful。Web 应用程序最重要的 REST 原则是,客户端和服务器之间的交互在请求之间是无状态的。从客户端到服务器的每个请求都必须包含理解请求所必需的信息。如果服务器在请求之间的任何时间点重启,客户端不会得到通知。此外,无状态请求可以由任何可用服务器回答,这十分适合云计算之类的环境。客户端可以缓存数据以改进性能。
在服务器端,应用程序状态和功能可以分为各种资源。资源是一个有趣的概念实体,它向客户端公开。资源的例子有:应用程序对象、数据库记录、算法等等。每个资源都使用 URI(Universal Resource Identifier) 得到一个唯一的地址。所有资源都共享统一的接口,以便在客户端和服务器之间传输状态。使用的是标准的 HTTP 方法,比如 GET、 PUT、 POST 和DELETE。
在 REST 样式的 Web 服务中,每个资源都有一个地址。资源本身都是方法调用的目标,方法列表对所有资源都是一样的。这些方法都是标准方法,包括 HTTP GET、 POST、PUT、 DELETE,还可能包括 HEAD 和 OPTIONS。简单的理解就是,如果想要访问互联网上的资源,就必须向资源所在的服务器发出请求,请求体中必须包含资源的网络路径, 以及对资源进行的操作(增删改查)。
REST 样式的 Web 服务若有返回结果,大多数以JSON字符串形式返回。
ElasticSearch是面向文档型数据库,一条数据就是一个文档,将ElasticSearch里存储文档数据和MySQL存储数据的概念进行一个类比:
ES里的Index可以看做一个库,而Types相当于表,Documents则相当于表的行
ES6.X中,一个index下只能包含一个type,ES7.X中,Type的概念已被删除
6用JSON作为文档序列化的格式,比如一条用户信息:
正排索引(传统)
倒排索引
对比关系型数据库,创建索引就等同于创建数据库。
在 Postman 中,向 ES 服务器发 PUT 请求 : http://127.0.0.1:9200/shopping
请求后,服务器返回响应:
如果重复发 PUT 请求 : http://127.0.0.1:9200/shopping 添加索引,会返回错误信息 :
在 Postman 中,向 ES 服务器发 GET 请求 : http://127.0.0.1:9200/_cat/indices?v
这里请求路径中的_cat 表示查看的意思, indices 表示索引,所以整体含义就是查看当前 ES服务器中的所有索引,就好像 MySQL 中的 show tables 的感觉,服务器响应结果如下 :
在 Postman 中,向 ES 服务器发 GET 请求 : http://127.0.0.1:9200/shopping
查看索引向ES服务器发送的请求路径和创建索引是一致的,但是HTTP方法不一致,这里可以体会一下RESTful的意义,请求后,服务器响应结果如下:
在 Postman 中,向 ES 服务器发 DELETE 请求 : http://127.0.0.1:9200/shopping
返回结果如下:
重新访问索引时,服务器返回响应:索引不存在
假设索引已经创建好了,接下来我们来创建文档,并添加数据。这里的文档可以类比为关系型数据库中的表数据,添加的数据格式为 JSON 格式
在 Postman 中,向 ES 服务器发 POST 请求 : http://127.0.0.1:9200/shopping/_doc,
请求体JSON内容为:
注意,此处发送请求的方式必须为 POST,不能是 PUT,否则会发生错误。
服务器响应结果如下:
上面的数据创建后,由于没有指定数据唯一性标识(ID),默认情况下, ES 服务器会随机生成一个。
如果想要自定义唯一性标识,需要在创建时指定: http://127.0.0.1:9200/shopping/_doc/1,请求体JSON内容为:
此处需要注意:如果增加数据时明确数据主键,那么请求方式也可以为 PUT。
查看文档时,需要指明文档的唯一性标识,类似于 MySQL 中数据的主键查询
在 Postman 中,向 ES 服务器发 GET 请求 : http://127.0.0.1:9200/shopping/_doc/1 。
返回结果如下:
查找不存在的内容,向 ES 服务器发 GET 请求 : http://127.0.0.1:9200/shopping/_doc/1001。
返回结果如下:
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "1001",
- "found": false
- }
查看索引下所有数据,向 ES 服务器发 GET 请求 : http://127.0.0.1:9200/shopping/_search。
返回结果如下:
- {
- "took": 133,
- "timed_out": false,
- "_shards": {
- "total": 1,
- "successful": 1,
- "skipped": 0,
- "failed": 0
- },
- "hits": {
- "total": {
- "value": 2,
- "relation": "eq"
- },
- "max_score": 1,
- "hits": [
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "ANQqsHgBaKNfVnMbhZYU",
- "_score": 1,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 3999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "1",
- "_score": 1,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 3999
- }
- }
- ]
- }
- }
和新增文档一样,输入相同的 URL 地址请求,如果请求体变化,会将原有的数据内容覆盖
在 Postman 中,向 ES 服务器发 POST 请求 : http://127.0.0.1:9200/shopping/_doc/1
请求体JSON内容为:
修改成功后,服务器响应结果:
修改数据时,也可以只修改某一给条数据的局部信息
在 Postman 中,向 ES 服务器发 POST 请求 : http://127.0.0.1:9200/shopping/_update/1。
请求体JSON内容为:
返回结果如下:
根据唯一性标识,查询文档数据,文档数据已经更新
删除一个文档不会立即从磁盘上移除,它只是被标记成已删除(逻辑删除)。
在 Postman 中,向 ES 服务器发 DELETE 请求 : http://127.0.0.1:9200/shopping/_doc/1
返回结果:
删除后再查询当前文档信息
如果删除一个并不存在的文档
一般删除数据都是根据文档的唯一性标识进行删除,实际操作时,也可以根据条件对多条数据进行删除
首先分别添加多条数据:
向ES服务器发POST请求:http://127.0.0.1:9200/shopping/_delete_by_query
请求体内容为:
删除成功后,服务器响应结果:
假设有以下文档内容,在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search:
- {
- "took": 5,
- "timed_out": false,
- "_shards": {
- "total": 1,
- "successful": 1,
- "skipped": 0,
- "failed": 0
- },
- "hits": {
- "total": {
- "value": 6,
- "relation": "eq"
- },
- "max_score": 1,
- "hits": [
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "ANQqsHgBaKNfVnMbhZYU",
- "_score": 1,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 3999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "A9R5sHgBaKNfVnMb25Ya",
- "_score": 1,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "BNR5sHgBaKNfVnMb7pal",
- "_score": 1,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "BtR6sHgBaKNfVnMbX5Y5",
- "_score": 1,
- "_source": {
- "title": "华为手机",
- "category": "华为",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "B9R6sHgBaKNfVnMbZpZ6",
- "_score": 1,
- "_source": {
- "title": "华为手机",
- "category": "华为",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "CdR7sHgBaKNfVnMbsJb9",
- "_score": 1,
- "_source": {
- "title": "华为手机",
- "category": "华为",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- }
- }
- ]
- }
- }
查找category为小米的文档,在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search?q=category:小米,返回结果如下:
- {
- "took": 94,
- "timed_out": false,
- "_shards": {
- "total": 1,
- "successful": 1,
- "skipped": 0,
- "failed": 0
- },
- "hits": {
- "total": {
- "value": 3,
- "relation": "eq"
- },
- "max_score": 1.3862942,
- "hits": [
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "ANQqsHgBaKNfVnMbhZYU",
- "_score": 1.3862942,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 3999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "A9R5sHgBaKNfVnMb25Ya",
- "_score": 1.3862942,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "BNR5sHgBaKNfVnMb7pal",
- "_score": 1.3862942,
- "_source": {
- "title": "小米手机",
- "category": "小米",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- }
- }
- ]
- }
- }
上述为URL带参数形式查询,这很容易让不善者心怀恶意,或者参数值出现中文会出现乱码情况。为了避免这些情况,我们可用使用带JSON请求体请求进行查询。
接下带JSON请求体,还是查找category为小米的文档,在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match":{
- "category":"小米"
- }
- }
- }
返回结果如下:
{ "took": 3, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 3, "relation": "eq" }, "max_score": 1.3862942, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 1.3862942, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": 1.3862942, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BNR5sHgBaKNfVnMb7pal", "_score": 1.3862942, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } } ] } }
查找所有文档内容,也可以这样,在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match_all":{}
- }
- }
则返回所有文档内容:
{ "took": 2, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": 1, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BNR5sHgBaKNfVnMb7pal", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BtR6sHgBaKNfVnMbX5Y5", "_score": 1, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "B9R6sHgBaKNfVnMbZpZ6", "_score": 1, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "CdR7sHgBaKNfVnMbsJb9", "_score": 1, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } } ] } }
如果想查询指定字段,在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match_all":{}
- },
- "_source":["title"]
- }
返回结果如下:
{ "took": 5, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": 1, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 1, "_source": { "title": "小米手机" } }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": 1, "_source": { "title": "小米手机" } }, { "_index": "shopping", "_type": "_doc", "_id": "BNR5sHgBaKNfVnMb7pal", "_score": 1, "_source": { "title": "小米手机" } }, { "_index": "shopping", "_type": "_doc", "_id": "BtR6sHgBaKNfVnMbX5Y5", "_score": 1, "_source": { "title": "华为手机" } }, { "_index": "shopping", "_type": "_doc", "_id": "B9R6sHgBaKNfVnMbZpZ6", "_score": 1, "_source": { "title": "华为手机" } }, { "_index": "shopping", "_type": "_doc", "_id": "CdR7sHgBaKNfVnMbsJb9", "_score": 1, "_source": { "title": "华为手机" } } ] } }
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match_all":{}
- },
- "from":0,
- "size":2
- }
返回结果如下:
{ "took": 1, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": 1, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } } ] } }
如果想通过排序查出价格最高的手机,在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match_all":{}
- },
- "sort":{
- "price":{
- "order":"desc"
- }
- }
- }
返回结果如下:
{ "took": 96, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": null, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": null, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 }, "sort": [ 3999 ] }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": null, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 }, "sort": [ 1999 ] }, { "_index": "shopping", "_type": "_doc", "_id": "BNR5sHgBaKNfVnMb7pal", "_score": null, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 }, "sort": [ 1999 ] }, { "_index": "shopping", "_type": "_doc", "_id": "BtR6sHgBaKNfVnMbX5Y5", "_score": null, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 }, "sort": [ 1999 ] }, { "_index": "shopping", "_type": "_doc", "_id": "B9R6sHgBaKNfVnMbZpZ6", "_score": null, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 }, "sort": [ 1999 ] }, { "_index": "shopping", "_type": "_doc", "_id": "CdR7sHgBaKNfVnMbsJb9", "_score": null, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 }, "sort": [ 1999 ] } ] } }
假设想找出小米牌子,价格为3999元的。(must相当于数据库的&&)
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "bool":{
- "must":[{
- "match":{
- "category":"小米"
- }
- },{
- "match":{
- "price":3999.00
- }
- }]
- }
- }
- }
返回结果如下:
{ "took": 134, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 1, "relation": "eq" }, "max_score": 2.3862944, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 2.3862944, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } } ] } }
假设想找出小米和华为的牌子。(should相当于数据库的||)
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
{ "query":{ "bool":{ "should":[{ "match":{ "category":"小米" } },{ "match":{ "category":"华为" } }] }, "filter":{ "range":{ "price":{ "gt":2000 } } } } }
返回结果如下:
{ "took": 8, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": 1.3862942, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 1.3862942, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": 1.3862942, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BNR5sHgBaKNfVnMb7pal", "_score": 1.3862942, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BtR6sHgBaKNfVnMbX5Y5", "_score": 1.3862942, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "B9R6sHgBaKNfVnMbZpZ6", "_score": 1.3862942, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "CdR7sHgBaKNfVnMbsJb9", "_score": 1.3862942, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } } ] } }
假设想找出小米和华为的牌子,价格大于2000元的手机。
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
{ "query":{ "bool":{ "should":[{ "match":{ "category":"小米" } },{ "match":{ "category":"华为" } }], "filter":{ "range":{ "price":{ "gt":2000 } } } } } }
返回结果如下:
{ "took": 72, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 1, "relation": "eq" }, "max_score": 1.3862942, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 1.3862942, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } } ] } }
这功能像搜索引擎那样,如品牌输入“小华”,返回结果带回品牌有“小米”和“华为”的。
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match":{
- "category" : "小华"
- }
- }
- }
返回结果如下:
{ "took": 7, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": 0.6931471, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 0.6931471, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": 0.6931471, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BNR5sHgBaKNfVnMb7pal", "_score": 0.6931471, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BtR6sHgBaKNfVnMbX5Y5", "_score": 0.6931471, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "B9R6sHgBaKNfVnMbZpZ6", "_score": 0.6931471, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "CdR7sHgBaKNfVnMbsJb9", "_score": 0.6931471, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } } ] } }
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match_phrase":{
- "category" : "为"
- }
- }
- }
返回结果如下:
{ "took": 2, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 3, "relation": "eq" }, "max_score": 0.6931471, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "BtR6sHgBaKNfVnMbX5Y5", "_score": 0.6931471, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "B9R6sHgBaKNfVnMbZpZ6", "_score": 0.6931471, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "CdR7sHgBaKNfVnMbsJb9", "_score": 0.6931471, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } } ] } }
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "query":{
- "match_phrase":{
- "category" : "为"
- }
- },
- "highlight":{
- "fields":{
- "category":{}//<----高亮这字段
- }
- }
- }
返回结果如下:
- {
- "took": 100,
- "timed_out": false,
- "_shards": {
- "total": 1,
- "successful": 1,
- "skipped": 0,
- "failed": 0
- },
- "hits": {
- "total": {
- "value": 3,
- "relation": "eq"
- },
- "max_score": 0.6931471,
- "hits": [
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "BtR6sHgBaKNfVnMbX5Y5",
- "_score": 0.6931471,
- "_source": {
- "title": "华为手机",
- "category": "华为",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- },
- "highlight": {
- "category": [
- "华<em>为</em>"//<------高亮一个为字。
- ]
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "B9R6sHgBaKNfVnMbZpZ6",
- "_score": 0.6931471,
- "_source": {
- "title": "华为手机",
- "category": "华为",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- },
- "highlight": {
- "category": [
- "华<em>为</em>"
- ]
- }
- },
- {
- "_index": "shopping",
- "_type": "_doc",
- "_id": "CdR7sHgBaKNfVnMbsJb9",
- "_score": 0.6931471,
- "_source": {
- "title": "华为手机",
- "category": "华为",
- "images": "http://www.gulixueyuan.com/xm.jpg",
- "price": 1999
- },
- "highlight": {
- "category": [
- "华<em>为</em>"
- ]
- }
- }
- ]
- }
- }
聚合允许使用者对 es 文档进行统计分析,类似与关系型数据库中的 group by,当然还有很多其他的聚合,例如取最大值max、平均值avg等等。
接下来按price字段进行分组:
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "aggs":{//聚合操作
- "price_group":{//名称,随意起名
- "terms":{//分组
- "field":"price"//分组字段
- }
- }
- }
- }
返回结果如下:
{ "took": 63, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": 1, "hits": [ { "_index": "shopping", "_type": "_doc", "_id": "ANQqsHgBaKNfVnMbhZYU", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 3999 } }, { "_index": "shopping", "_type": "_doc", "_id": "A9R5sHgBaKNfVnMb25Ya", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BNR5sHgBaKNfVnMb7pal", "_score": 1, "_source": { "title": "小米手机", "category": "小米", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "BtR6sHgBaKNfVnMbX5Y5", "_score": 1, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "B9R6sHgBaKNfVnMbZpZ6", "_score": 1, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } }, { "_index": "shopping", "_type": "_doc", "_id": "CdR7sHgBaKNfVnMbsJb9", "_score": 1, "_source": { "title": "华为手机", "category": "华为", "images": "http://www.gulixueyuan.com/xm.jpg", "price": 1999 } } ] }, "aggregations": { "price_group": { "doc_count_error_upper_bound": 0, "sum_other_doc_count": 0, "buckets": [ { "key": 1999, "doc_count": 5 }, { "key": 3999, "doc_count": 1 } ] } } }
上面返回结果会附带原始数据的。若不想要不附带原始数据的结果,在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "aggs":{
- "price_group":{
- "terms":{
- "field":"price"
- }
- }
- },
- "size":0
- }
返回结果如下:
{ "took": 60, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": null, "hits": [] }, "aggregations": { "price_group": { "doc_count_error_upper_bound": 0, "sum_other_doc_count": 0, "buckets": [ { "key": 1999, "doc_count": 5 }, { "key": 3999, "doc_count": 1 } ] } } }
若想对所有手机价格求平均值。
在 Postman 中,向 ES 服务器发 GET请求 : http://127.0.0.1:9200/shopping/_search,附带JSON体如下:
- {
- "aggs":{
- "price_avg":{//名称,随意起名
- "avg":{//求平均
- "field":"price"
- }
- }
- },
- "size":0
- }
返回结果如下:
{ "took": 14, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 6, "relation": "eq" }, "max_score": null, "hits": [] }, "aggregations": { "price_avg": { "value": 2332.3333333333335 } } }
有了索引库,等于有了数据库中的 database。
接下来就需要建索引库(index)中的映射了,类似于数据库(database)中的表结构(table)。
创建数据库表需要设置字段名称,类型,长度,约束等;索引库也一样,需要知道这个类型下有哪些字段,每个字段有哪些约束信息,这就叫做映射(mapping)。
先创建一个索引:
# PUT http://127.0.0.1:9200/user
返回结果:
- {
- "acknowledged": true,
- "shards_acknowledged": true,
- "index": "user"
- }
创建映射:
# PUT http://127.0.0.1:9200/user/_mapping { "properties": { "name":{ "type": "text", "index": true }, "sex":{ "type": "keyword", "index": true }, "tel":{ "type": "keyword", "index": false } } }
返回结果如下:
- {
- "acknowledged": true
- }
#GET http://127.0.0.1:9200/user/_mapping
返回结果如下:
{ "user": { "mappings": { "properties": { "name": { "type": "text" }, "sex": { "type": "keyword" }, "tel": { "type": "keyword", "index": false } } } } }
增加数据:
- #PUT http://127.0.0.1:9200/user/_create/1001
- {
- "name":"小米",
- "sex":"男的",
- "tel":"1111"
- }
返回结果如下:
- {
- "_index": "user",
- "_type": "_doc",
- "_id": "1001",
- "_version": 1,
- "result": "created",
- "_shards": {
- "total": 2,
- "successful": 1,
- "failed": 0
- },
- "_seq_no": 0,
- "_primary_term": 1
- }
查找name含有”小“数据:
- #GET http://127.0.0.1:9200/user/_search
- {
- "query":{
- "match":{
- "name":"小"
- }
- }
- }
返回结果如下:
{ "took": 495, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 1, "relation": "eq" }, "max_score": 0.2876821, "hits": [ { "_index": "user", "_type": "_doc", "_id": "1001", "_score": 0.2876821, "_source": { "name": "小米", "sex": "男的", "tel": "1111" } } ] } }
查找sex含有”男“数据:
- #GET http://127.0.0.1:9200/user/_search
- {
- "query":{
- "match":{
- "sex":"男"
- }
- }
- }
返回结果如下:
{ "took": 1, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 0, "relation": "eq" }, "max_score": null, "hits": [] } }
找不想要的结果,只因创建映射时"sex"的类型为"keyword"。
"sex"只能完全为”男的“,才能得出原数据。
- #GET http://127.0.0.1:9200/user/_search
- {
- "query":{
- "match":{
- "sex":"男的"
- }
- }
- }
返回结果如下:
{ "took": 2, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 1, "relation": "eq" }, "max_score": 0.2876821, "hits": [ { "_index": "user", "_type": "_doc", "_id": "1001", "_score": 0.2876821, "_source": { "name": "小米", "sex": "男的", "tel": "1111" } } ] } }
查询电话
- # GET http://127.0.0.1:9200/user/_search
- {
- "query":{
- "match":{
- "tel":"11"
- }
- }
- }
返回结果如下:
{ "error": { "root_cause": [ { "type": "query_shard_exception", "reason": "failed to create query: Cannot search on field [tel] since it is not indexed.", "index_uuid": "ivLnMfQKROS7Skb2MTFOew", "index": "user" } ], "type": "search_phase_execution_exception", "reason": "all shards failed", "phase": "query", "grouped": true, "failed_shards": [ { "shard": 0, "index": "user", "node": "4P7dIRfXSbezE5JTiuylew", "reason": { "type": "query_shard_exception", "reason": "failed to create query: Cannot search on field [tel] since it is not indexed.", "index_uuid": "ivLnMfQKROS7Skb2MTFOew", "index": "user", "caused_by": { "type": "illegal_argument_exception", "reason": "Cannot search on field [tel] since it is not indexed." } } } ] }, "status": 400 }
报错只因创建映射时"tel"的"index"为false。
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