6.1、ES搜索详解 —— 搜索机制

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本章参考文档：https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-percolate-query.html
注意文档对应的Elasticsearch版本

索引过程：

第2象限 有 原始文档；

Elasticsearch 保存 文档的原始内容 和 对应的倒排序索引文件；

搜索过程：

在 倒排索引文件 维护的 倒排记录表 找 关键词 对应的 文档集合，然后做评分、排序、高亮，将结果返回给用户；

过滤机制：

根据条件对文档进行过滤，不计算评分；

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DELETE books
PUT books
{
  "settings": {
    "number_of_replicas": 1,
    "number_of_shards": 3
  },
  "mappings": {
    "properties": {
      "id": {
        "type": "long"
      },
      "title": {
        "type": "text",
        "analyzer": "ik_max_word"
      },
      "language": {
        "type": "keyword"
      },
      "author": {
        "type": "keyword"
      },
      "price": {
        "type": "double"
      },
      "publish_time": {
        "type": "date",
        "format": "yyyy-MM-dd"
      },
      "desc": {
        "type": "text",
        "analyzer": "ik_max_word"
      }
    }
  }
}
PUT books/_doc/1
{
  "id":1,
  "title":"Java编程思想",
  "language":"Java",
  "author": "Bruce Eckel",
  "price":70.20,
  "publish_time":"2017-01-02",
  "desc":"Java学习必读经典，殿堂级著作！赢得全球程序员的广泛赞誉。"
}
PUT books/_doc/2
{
  "id":2,
  "title":"Java程序性能优化",
  "language":"Java",
  "author": "葛一鸣",
  "price":46.50,
  "publish_time":"2012-08-02",
  "desc":"Java程序更快，更稳定。深入剖析软件设计层面、代码层面、JVM层面的优化方法。"
}
PUT books/_doc/3
{
  "id":3,
  "title":"Python科学计算",
  "language":"python",
  "author": "张若愚",
  "price":81.40,
  "publish_time":"2014-01-02",
  "desc":"零基础学python， 光盘中坐着度假开发winPython运行环境，涵盖了Python各个扩展库。"
}
PUT books/_doc/4
{
  "id":4,
  "title":"Python基础教程",
  "language":"python",
  "author": "Helant",
  "price":54.50,
  "publish_time":"2014-03-02",
  "desc":"经典的python入门教程，层次鲜明，结构严谨，内容详实。"
}
PUT books/_doc/5
{
  "id":5,
  "title":"JavaScript高级程序设计",
  "language":"javascript",
  "author": "Nicholas C. Zakas",
  "price":66.40,
  "publish_time":"2012-03-02",
  "desc":"JavaScript 技术经典名著。"
}
GET books/_mapping

match_all搜索,简化语法：
GET books/_search
term query 搜索：
GET books/_search
{
  "query": {
    "term": {
      "title": "思想"
    }
  }
}

数据量很大的情况下，需要分页：

from：开始位置

size：返回文档最大数量

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GET books/_search
{
  "from": 1,
  "size": 2,
  "query": {
    "term": {
      "title": "java"
    }
  }
}

最小评分过滤机制：

相关文档很多的情况下，相关性比较低的文档可以过滤掉

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GET books/_search
{
  "min_score": 0.6,
  "query": {
    "term": {
      "title": "java"
    }
  }
}

高亮查询关键字：

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GET books/_search
{
  "query": {
    "term": {
      "title": "java"
    }
  },
  "highlight": {
    "fields": {
      "title": {}
    }
  }
}