Elasticsearch(4) filter的使用_elasticsearch filter

elasticsearch version： 7.10.1

filter介绍

在Elasticsearch中，filter主要用于过滤文档，它与query的主要区别在于filter不计算相关性得分，而是返回简单的布尔匹配结果（匹配或不匹配），并且可以被缓存以提高性能。filter通常用于预筛选阶段，尤其是对于那些频繁使用的过滤条件。

filter语法

1. Term Filter：

{
  "query": {
    "bool": {
      "filter": {
        "term": {
          "field_name": "value" 
        }
      }
    }
  }
}
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2. Range Filter

{
  "query": {
    "bool": {
      "filter": {
        "range": {
          "age": {
            "gte": 18,
            "lte": 30
          }
        }
      }
    }
  }
}
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3. Exists Filter

{
  "query": {
    "bool": {
      "filter": {
        "exists": {
          "field": "category"
        }
      }
    }
  }
}
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4. List item

{
  "query": {
    "bool": {
      "filter": {
        "terms": {
          "tags": ["tag1", "tag2"]
        }
      }
    }
  }
}
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5. And/Or Filters

{
  "query": {
    "bool": {
      "filter": [
        { "term": { "color": "red" } },
        { "term": { "size": "large" } }
      ]
    }
  }
}
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查询流程

1. 对每个filter条件进行布尔运算，决定哪些文档满足所有条件。由于filter不计算相关性得分，所以这一阶段非常快速，而且结果可以被缓存以优化后续的相同过滤查询

案例

场景

假设我们有一个电商产品索引，其中包含商品的详细信息，如product_id（产品ID）、name（产品名称）、category（产品类别）、price（价格）和brand（品牌）。现在我们需要创建一个索引，并插入大量文档，然后编写一个过滤查询，查找所有价格在一定范围内的电子产品（类别为electronics）。

索引创建

PUT /products
{
  "mappings": {
    "properties": {
      "product_id": { "type": "keyword" },
      "name": { "type": "text" },
      "category": { "type": "keyword" },
      "price": { "type": "double" },
      "brand": { "type": "keyword" }
    }
  }
}
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文档插入

 POST /products/_bulk
{ "index": {} }
{ "product_id": "1", "name": "Apple iPhone X", "category": "electronics", "price": 999.99, "brand": "Apple" }
{ "index": {} }
{ "product_id": "2", "name": "Samsung Galaxy S20", "category": "electronics", "price": 799.99, "brand": "Samsung" }
{ "index": {} }
{ "product_id": "3", "name": "Bose QuietComfort Headphones", "category": "electronics", "price": 349.99, "brand": "Bose" }
POST /products/_bulk
{ "index": {} }
{ "product_id": "4", "name": "Dell XPS 13 Laptop", "category": "electronics", "price": 1299.99, "brand": "Dell" }
{ "index": {} }
{ "product_id": "5", "name": "Sony Alpha a7 III Camera", "category": "electronics", "price": 1999.99, "brand": "Sony" }
{ "index": {} }
{ "product_id": "6", "name": "Logitech MX Master 3 Mouse", "category": "electronics", "price": 99.99, "brand": "Logitech" }
{ "index": {} }
{ "product_id": "7", "name": "Microsoft Surface Pro 7", "category": "electronics", "price": 799.99, "brand": "Microsoft" }
{ "index": {} }
{ "product_id": "8", "name": "GoPro HERO9 Black Action Camera", "category": "electronics", "price": 399.99, "brand": "GoPro" }
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查询语句

GET /products/_search
{
  "query": {
    "bool": {
      "filter": [
        { "term": { "category": "electronics" } },
        { "range": {
            "price": {
              "gte": 500.00,
              "lte": 1000.00
            }
          }
        }
      ]
    }
  }
}
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