ES系列、Elasticsearch Suggester API(自动补全）

向右看齐 2024-04-08 10:22 105阅读 0赞

## 1.概念 ##

### 1.1 补全api主要分为四类 ###

1.  Term Suggester（纠错补全，输入错误的情况下补全正确的单词）
2.  Phrase Suggester（自动补全短语，输入一个单词补全整个短语）
3.  Completion Suggester(完成补全单词，输出如前半部分，补全整个单词）
4.  Context Suggester（上下文补全）

整体效果类似百度搜索，如图：

![9d4bc5bf80f1b52d50e037fd523a73ff.png][]

## 2. Completion suggester 自动补全 ##

针对自动补全场景而设计的建议器。此场景下用户每输入一个字符的时候，就需要即时发送一次查询请求到后端查找匹配项，在用户输入速度较高的情况下对后端响应速度要求比较苛刻。因此实现上它和前面两个Suggester采用了不同的数据结构，索引并非通过倒排来完成，而是将analyze过的数据编码成FST和索引一起存放。对于一个open状态的索引，FST会被ES整个装载到内存里的，进行前缀查找速度极快。但是FST只能用于前缀查找，这也是Completion Suggester的局限所在**。**

### **2.1建立索引** ###

put  /book
    
    {
        "mappings": {
            "music" : {
                "properties" : {
                    "suggest" : {
                        "type" : "completion"
                    },
                    "title" : {
                        "type": "keyword"
                    }
                }
            }
        }
    }
    
    注意，最终写入数据需要 /book/music

### 2.2插入数据 ###

put /book/music/_doc/1
    {
        "suggest":"爱一个人好难"
    }
    
    put /book/music/_doc/2
    {
        "suggest":"爱一个人好难"
    }
    
    put /book/music/_doc/3
    {
        "suggest":"爱真的需要勇气"
    }

### 2.3自动补全查询 ###

示例1：查询建议根据前缀查询

POST book/music/_search
    {
        "suggest": {
            "song-suggest" : {
                "prefix" : "爱",
                "completion" : {
                    "field" : "suggest"
                }
            }
        }
    }

#### 示例1：查询建议根据前缀查询结果 ####

{
        "took": ,
        "timed_out": false,
        "_shards": {
            "total": ,
            "successful": ,
            "skipped": ,
            "failed":
        },
        "hits": {
            "total": ,
            "max_score": ,
            "hits": []
        },
        "suggest": {
            "song-suggest": [
                {
                    "text": "te",
                    "offset": ,
                    "length": ,
                    "options": [
                        {
                            "text": "爱一个人好难",
                            "_index": "book",
                            "_type": "music",
                            "_id": "6Xu6mmUBYLvVFwGWpXeL",
                            "_score": ,
                            "_source": {
                                "suggest": "爱一个人好难"
                            }
                        },
                        {
                            "text": "爱一个人好难",
                            "_index": "book",
                            "_type": "music",
                            "_id": "6nu8mmUBYLvVFwGWSndC",
                            "_score": ,
                            "_source": {
                                "suggest": "爱一个人好难"
                            }
                        },
                        {
                            "text": "爱真的需要勇气",
                            "_index": "book",
                            "_type": "music",
                            "_id": "63u8mmUBYLvVFwGWZHdC",
                            "_score": ,
                            "_source": {
                                "suggest": "爱真的需要勇气"
                            }
                        }
                    ]
                }
            ]
        }
    }

#### 示例2：对建议查询结果去重 ####

{
        "suggest": {
            "song-suggest" : {
                "prefix" : "爱",
                "completion" : {
                    "field" : "suggest" ,
                     "skip_duplicates": true
                }
            }
        }
    }

本文部分参考：《[ES系列十三、Elasticsearch Suggester API(自动补全）][ES_Elasticsearch Suggester API]》 里面有整个四种补全的方式。

[9d4bc5bf80f1b52d50e037fd523a73ff.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/08/2fb796b2e8f04060b40b48e9809a7e0e.png
[ES_Elasticsearch Suggester API]: https://www.bbsmax.com/A/Vx5MYLDY5N/