Elasticsearch(038)：es中搜索之入门与分页搜索

╰半夏微凉° 2022-12-23 06:52 232阅读 0赞

ES中搜索的方式分为`两种`，一种是通过`URL参数`进行搜索；另一种是通过`POST`中`body请求参数`进行搜索。

针对第一种我们进行简单的讲解，我们关注的核心放在第二种上面。

# 一、简单搜索(search) #

## 1.1 测试使用的index、mapping及数据准备 ##

PUT example
    PUT example/docs/_mapping
    { 
        "properties": { 
            "id": { 
                "type": "long"
            },
            "orderNo": { 
                "type": "keyword"
            },
            "buyerId": { 
                "type": "long"
            },
            "shopId": { 
                "type": "long"
            },
            "shopName": { 
                "type": "text",
                "analyzer":"ik_max_word",
                "search_analyzer":"ik_smart",
                "fields": { 
                    "keyword": { 
                        "type": "keyword"
                    }
                }
            },
            "tradeStatus": { 
                "type": "integer"
            },
            "payStatus": { 
                "type": "integer"
            },
            "orderAmount": { 
                "type": "float"
            },
            "payAmount": { 
                "type": "float"
            },
            "payPlatformOrderNo": { 
                "type": "keyword"
            },
            "delivery": { 
                "properties": { 
                    "receiver": { 
                        "type": "keyword"
                    },
                    "phoneNumber": { 
                        "type": "keyword"
                    },
                    "address": { 
                        "type": "keyword"
                    },
                    "detailedAddress": { 
                        "type": "keyword"
                    }
                }
            },
            "items": { 
                "type": "nested",
                "properties": { 
                    "id": { 
                        "type": "long"
                    },
                    "orderId": { 
                        "type": "long"
                    },
                    "goodId": { 
                        "type": "long"
                    },
                    "goodName": { 
                        "type": "keyword"
                    },
                    "goodPrice": { 
                        "type": "float"
                    },
                    "goodNumber": { 
                        "type": "integer"
                    },
                    "goodAmount": { 
                        "type": "float"
                    },
                    "createTime": { 
                        "type": "date",
                        "format": "yyyy-MM-dd HH:mm:ss",
                        "ignore_malformed": true
                    }
                }
            },
            "createTime": { 
                "type": "date",
                "format": "yyyy-MM-dd HH:mm:ss",
                "ignore_malformed": true
            },
            "deliveryTime": { 
                "type": "date",
                "format": "yyyy-MM-dd HH:mm:ss",
                "ignore_malformed": false
            },
            "deliveryAmount": { 
                "type": "float"
            },
            "remark": { 
                "type": "text",
                "analyzer":"ik_max_word",
                "search_analyzer":"ik_smart"
            }
        }
    }
    
    #bulk插入
    POST example/docs/_bulk
    { "index": { "_id": 1}}
    { "id":1,"orderNo":1136482742505680898,"buyerId":4500,"shopId":9596,"shopName":"小米手机官方旗舰店","tradeStatus":1,"payStatus":1,"orderAmount":4290.90,"payAmount":4280.00,"payPlatformOrderNo":"9b235e16-ffa2-4605-af8c-47bee94d1732","delivery":{ "receiver":"张三","phoneNumber":"13279220508","address":"陕西省西安市雁塔区","detailedAddress":"小寨东路91号陕西历史博物馆"},"items":[{ "id":123,"orderId":1,"goodId":54,"goodName":"小米CC9Pro","goodPrice":3299.00,"goodNumber":5468,"goodAmount":1,"createTime":"2019-11-11 00:01:18"},{ "id":124,"orderId":1,"goodId":55,"goodName":"小米插线板","goodPrice":49.00,"goodNumber":5469,"goodAmount":2,"createTime":"2019-11-11 00:01:18"},{ "id":125,"orderId":1,"goodId":56,"goodName":"小米平衡车","goodPrice":1999.00,"goodNumber":5470,"goodAmount":1,"createTime":"2019-11-11 00:01:18"}],"createTime":"2019-11-11 00:01:18","deliveryTime":"2019-11-11 16:30:22","deliveryAmount":20.00,"remark":"尽快发货，谢谢！"}
    { "index": { "_id": 2}}
    { "id":2,"orderNo":1136482742505656781,"buyerId":4500,"shopId":9500,"shopName":"华为旗舰店","tradeStatus":1,"payStatus":1,"orderAmount":7999.99,"payAmount":6500.00,"payPlatformOrderNo":"9b235e16-ffa2-4605-af8c-47bee94d2134","delivery":{ "receiver":"张三","phoneNumber":"13279220508","address":"陕西省西安市雁塔区","detailedAddress":"小寨东路91号陕西历史博物馆"},"items":[{ "id":124,"orderId":2,"goodId":1003,"goodName":"华为笔记本","goodPrice":7999.99,"goodNumber":5400,"goodAmount":1,"createTime":"2019-11-11 00:01:18"}],"createTime":"2019-11-11 00:01:18","deliveryTime":"2019-11-12 18:30:22","deliveryAmount":0.00,"remark":"尽快发货，谢谢！"}
    { "index": { "_id": 3}}
    { "id":3,"orderNo":1136482742505655433,"buyerId":4501,"shopId":8503,"shopName":"无印良品旗舰店","tradeStatus":1,"payStatus":1,"orderAmount":2036.00,"payAmount":2020.00,"payPlatformOrderNo":"9b235e16-ffa2-4605-af8c-47bee94d2300","delivery":{ "receiver":"李四","phoneNumber":"13279228888","address":"陕西省西安市长安区","detailedAddress":"西长安街1号大厦"},"items":[{ "id":620,"orderId":3,"goodId":8784,"goodName":"柔和洗面奶","goodPrice":79.90,"goodNumber":8780,"goodAmount":1,"createTime":"2019-11-11 00:21:50"},{ "id":622,"orderId":3,"goodId":8704,"goodName":"化妆水","goodPrice":109.90,"goodNumber":8580,"goodAmount":2,"createTime":"2019-11-11 00:21:50"}],"createTime":"2019-11-11 00:21:50","deliveryTime":"2019-11-13 17:35:23","deliveryAmount":8.00,"remark":"尽快发货，谢谢！"}

## 1.2 示例 ##

在这里我们只做简单的示例，不做过多的学习，有过Http基础的话，基本没有什么难度。

#查询所有
    GET example/docs/_search
    
    #带有参数的查询
    GET example/docs/_search?
    
    #在索引example和us的所有类型中搜索
    GET example,us/_search
    
    # 在以g或u开头的索引的所有类型中搜索
    GET e*,u*/_search
    
    #在索引example和us的类型为docs和docs2中搜索
    GET example,us/docs,docs2/_search

> 注意：当你搜索包含单一索引时，Elasticsearch转发搜索请求到这个索引的主分片或每个分片的复制分片上，然后聚集每个分片的结果。搜索包含多个索引也是同样的方式——只不过或有更多的分片被关联。

可以跟的参数如下图所示。其实这些方式归根到底第二种方式的功能是重合的。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zOTcyMzU0NA_size_16_color_FFFFFF_t_70_pic_center]

# 二、 结构化搜索(request body search) #

请求体的参数是`JSON`格式。这种JSON必须遵循`DSL(domain search language)`语法格式。在这里我们简单做一下示例使用。关于更多的查询和使用会在后续的文章逐一详细介绍。

## 2.1 查询所有 ##

GET example/docs/_search
    { 
      "query": { 
        "match_all": { }
      }
    }

## 2.2 分页搜索 ##

和`SQL`使用`LIMIT`关键字返回只有一页的结果一样，`Elasticsearch`接受`from`和`size`参数：

`size`: 结果数，默认`10`

`from`: 跳过开始的结果数，默认`0`。可理解成元素`开始的索引下标`。

*例如我们想分页搜索订单的第一页，每页显示2个。*

GET example/docs/_search
    { 
      "query": { 
        "match_all": { }
      },
      "from": 0,
      "size": 2
    }

应该当心分页太深或者一次请求太多的结果。结果在返回前会被排序。但是记住一个搜索请求常常涉及多个分片。每个分片生成自己排好序的结果，它们接着需要集中起来排序以确保整体排序正确。

> 小贴士

在集群系统中深度分页。为了理解为什么深度分页是有问题的，让我们假设在一个有5个主分片的索引中搜索。当我们请求结果的第一页（结果1到10）时，每个分片产生自己最顶端10个结果然后返回它们给请求节点(requesting node)，它再排序这所有的50个结果以选出顶端的10个结果。

现在假设我们请求第1000页——结果10001到10010。工作方式都相同，不同的是每个分片都必须产生顶端的10010个结果。然后请求节点排序这50050个结果并丢弃50040个！你可以看到在分布式系统中，排序结果的花费随着分页的深入而成倍增长。这也是为什么网络搜索引擎中任何语句不能返回多于10000个结果的原因（通常最大的分页数就是100页，比如说京东的评论数等等）。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zOTcyMzU0NA_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/65f1a2a149dc4cf2a7c49afcebfe138f.png